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  • VB.Net Create Database table from class property

    - by joeb
    I'm trying to create an inheritable class(OF t) in vb.net that I will pass it a class of objects. Inside the class of objects I want to use the class properties to create a corresponding database table. Like below Public Class SampleClass #Region "Properties" Private newPropertyValue As String Public Property NewProperty() As String Get Return newPropertyValue End Get Set(ByVal value As String) newPropertyValue = value End Set End Property #End Region Public Sub New() End Sub End Class I'm new to vb.net so I don't know my way around exactly. I was looking into class attributes for this action but they do not fully make sense to me yet. Thanks in advance.

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  • Query MS Access database in VB 2008

    - by Logan
    Hi, I added an Access database as a Data Source in VB 2008. I want to query this database and use the information in various ways throughout the program. For example, there is an Employee table with first/last names of employees. I have a combobox on my form that I want to display all of the employees. So I want to query the database for all the rows in the Employee table, and add them to the combobox as I go. I am familiar with SQL Syntax, so I am not asking how to write the query itself, but rather how to fetch rows in VB code (mimicking php's mysql_fetch_assoc and mysql_connect essentially) Thanks! Edit: Also, I want to know if I can query a DB if I don't add it as a data source (if I know the path name of the database)

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  • Passing parameters between Silverlight and ASP.NET – Part 1

    - by mohanbrij
    While working with Silverlight applications, we may face some scenarios where we may need to embed Silverlight as a component, like for e.g in Sharepoint Webpars or simple we can have the same with ASP.NET. The biggest challenge comes when we have to pass the parameters from ASP.NET to Silverlight components or back from Silverlight to ASP.NET. We have lots of ways we can do this, like using InitParams, QueryStrings, using HTML objects in Silverlight, etc. All these different techniques have some advantages or disadvantages or limitations. Lets see one by one why we should choose one and what are the ways to achieve the same. 1. InitParams: Lets start with InitParams, Start your Visual Studio 2010 IDE, and Create a Silverlight Application, give any name. Now go to the ASP.NET WebProject which is used to Host the Silverlight XAP component. You will find lots of different tags are used by Silverlight object as <params> tags. To use InitParams, Silverlight provides us with a tag called InitParams which we can use to pass parameters to Silverlight object from ASP.NET. 1: <object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%"> 2: <param name="source" value="ClientBin/SilverlightApp.xap"/> 3: <param name="onError" value="onSilverlightError" /> 4: <param name="background" value="white" /> 5: <param name="minRuntimeVersion" value="4.0.50826.0" /> 6: <param name="initparams" id="initParams" runat="server" value=""/> 7: <param name="autoUpgrade" value="true" /> 8: <a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=4.0.50826.0" style="text-decoration:none"> 9: <img src="http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight" style="border-style:none"/> 10: </a> 11: </object> Here in the code above I have included a initParam as a param tag (line 6), now in the page load I will add a line 1: initParams.Attributes.Add("value", "key1=Brij, key2=Mohan"); This basically add a value parameter inside the initParam. So thats all we need in our ASP.NET side, now coming to the Silverlight Code open the code behind of App.xaml and add the following lines of code. 1: private string firstKey, secondKey; 2: private void Application_Startup(object sender, StartupEventArgs e) 3: { 4: if (e.InitParams.ContainsKey("key1")) 5: this.firstKey = e.InitParams["key1"]; 6: if (e.InitParams.ContainsKey("key2")) 7: this.secondKey = e.InitParams["key2"]; 8: this.RootVisual = new MainPage(firstKey, secondKey); 9: } This code fetch the init params and pass it to our MainPage.xaml constructor, in the MainPage.xaml we can use these variables according to our requirement, here in this example I am simply displaying the variables in a Message Box. 1: public MainPage(string param1, string param2) 2: { 3: InitializeComponent(); 4: MessageBox.Show("Welcome, " + param1 + " " + param2); 5: } This will give you a sample output as Limitations: Depending on the browsers you have some limitation on the overall string length of the parameters you can pass. To get more details on this limitation, you can refer to this link :http://www.boutell.com/newfaq/misc/urllength.html 2. QueryStrings To show this example I am taking the scenario where we have a default.aspx page and we are going to the SIlverlightTestPage.aspx, and we have to work with the parameters which was passed by default.aspx in the SilverlightTestPage.aspx Silverlight Component. So first I will add a new page in my application which contains a button with ID =btnNext, and on click of the button I will redirect my page to my SilverlightTestAppPage.aspx with the required query strings. Code of Default.aspx 1: protected void btnNext_Click(object sender, EventArgs e) 2: { 3: Response.Redirect("~/SilverlightAppTestPage.aspx?FName=Brij" + "&LName=Mohan"); 4: } Code of MainPage.xaml.cs 1: public partial class MainPage : UserControl 2: { 3: public MainPage() 4: { 5: InitializeComponent(); 6: this.Loaded += new RoutedEventHandler(MainPage_Loaded); 7: } 8: 9: void MainPage_Loaded(object sender, RoutedEventArgs e) 10: { 11: IDictionary<string, string> qString = HtmlPage.Document.QueryString; 12: string firstName = string.Empty; 13: string lastName = string.Empty; 14: foreach (KeyValuePair<string, string> keyValuePair in qString) 15: { 16: string key = keyValuePair.Key; 17: string value = keyValuePair.Value; 18: if (key == "FName") 19: firstName = value; 20: else if (key == "LName") 21: lastName = value; 22: } 23: MessageBox.Show("Welcome, " + firstName + " " + lastName); 24: } 25: } Set the Startup page as Default.aspx, now run the application. This will give you the following output: Since here also you are using the Query Strings to pass your parameters, so you are depending on the browser capabilities of the length of the query strings it can pass. Here also you can refer the limitation which I have mentioned in my previous example for the length of parameters you can use.   3. Using HtmlPage.Document Silverlight to ASP.NET <—> ASP.NET to Silverlight: To show this I setup a sample Silverlight Application with Buttons Get Data and Set Data with the Data Text Box. In ASP.NET page I kep a TextBox to Show how the values passed to and From Silverlight to ASP.NET reflects back. My page with Silverlight control looks like this. When I Say Get Data it pulls the data from ASP.NET to Silverlight Control Text Box, and When I say Set data it basically Set the Value from Silverlight Control TextBox to ASP.NET TextBox. Now let see the code how it is doing. This is my ASP.NET Source Code. Here I have just created a TextBox named : txtData 1: <body> 2: <form id="form1" runat="server" style="height:100%"> 3: <div id="silverlightControlHost"> 4: ASP.NET TextBox: <input type="text" runat="server" id="txtData" value="Some Data" /> 5: <object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%"> 6: <param name="source" value="ClientBin/SilverlightApplication1.xap"/> 7: <param name="onError" value="onSilverlightError" /> 8: <param name="background" value="white" /> 9: <param name="minRuntimeVersion" value="4.0.50826.0" /> 10: <param name="autoUpgrade" value="true" /> 11: <a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=4.0.50826.0" style="text-decoration:none"> 12: <img src="http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight" style="border-style:none"/> 13: </a> 14: </object><iframe id="_sl_historyFrame" style="visibility:hidden;height:0px;width:0px;border:0px"></iframe> 15: </div> 16: </form> 17: </body> My actual logic for getting and setting the data lies in my Silverlight Control, this is my XAML code with TextBox and Buttons. 1: <Grid x:Name="LayoutRoot" Background="White" Height="100" Width="450" VerticalAlignment="Top"> 2: <Grid.ColumnDefinitions> 3: <ColumnDefinition Width="110" /> 4: <ColumnDefinition Width="110" /> 5: <ColumnDefinition Width="110" /> 6: <ColumnDefinition Width="110" /> 7: </Grid.ColumnDefinitions> 8: <TextBlock Text="Silverlight Text Box: " Grid.Column="0" VerticalAlignment="Center"></TextBlock> 9: <TextBox x:Name="DataText" Width="100" Grid.Column="1" Height="20"></TextBox> 10: <Button x:Name="GetData" Width="100" Click="GetData_Click" Grid.Column="2" Height="30" Content="Get Data"></Button> 11: <Button x:Name="SetData" Width="100" Click="SetData_Click" Grid.Column="3" Height="30" Content="Set Data"></Button> 12: </Grid> Now we have to write few lines of Button Events for Get Data and Set Data which basically make use of Windows.System.Browser namespace. 1: private void GetData_Click(object sender, RoutedEventArgs e) 2: { 3: DataText.Text = HtmlPage.Document.GetElementById("txtData").GetProperty("value").ToString(); 4: } 5:  6: private void SetData_Click(object sender, RoutedEventArgs e) 7: { 8: HtmlPage.Document.GetElementById("txtData").SetProperty("value", DataText.Text); 9: } That’s it so when we run this application my Form will look like this. 4. Using Object Serialization. This is a useful when we want to pass Objects of Data from our ASP.NET application to Silverlight Controls and back. This technique basically uses the above technique I mentioned in Pint 3 above. Since this itself is a length topic so details of this I am going to cover in Part 2 of this Post with Sample Code Example very soon.

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  • ASP.Net Webservice - Constructors with Parameters

    - by Ben
    Hi, I'm fairly new to WebService developement and have just set up my own webservice (ASP.Net 3.5, Visual Studio 2008 .asmx file). I can not find a way of setting up my webservice to take parameters on the constructor. If i create a constructor that takes parameters, it is not then shown when i hook up to the webservice from my application (it only shows a parameterless constructor). Am i missing something blatently obvious, or is this not possible (and why not)? Thanks.

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  • ASP.net Repeater Control Problem (nothing outputted)

    - by Phil
    I have the following db code in my usercontrol (content.ascx.vb): If did = 0 Then s = "select etc (statement works on server)" x = New SqlCommand(s, c) x.Parameters.Add("@contentid", Data.SqlDbType.Int) x.Parameters("@contentid").Value = contentid c.Open() r = x.ExecuteReader If r.HasRows Then Contactinforepeater.DataSource = r End If c.Close() r.Close() Else s = "select etc (statement works on server)" x = New SqlCommand(s, c) x.Parameters.Add("@contentid", SqlDbType.Int) x.Parameters("@contentid").Value = contentid x.Parameters.Add("@did", SqlDbType.Int) x.Parameters("@did").Value = did c.Open() r = x.ExecuteReader If r.HasRows Then Contactinforepeater.DataSource = r c.Close() r.Close() End If End If Then I have the following repeater control markup in my usercontrol (content.ascx): <asp:Repeater ID="Contactinforepeater" runat="server"> <HeaderTemplate> <h1>Contact Information</h1> </HeaderTemplate> <ItemTemplate> <table width="50%"> <tr> <td colspan="2"><%#Container.DataItem("position")%></td> </tr> <tr> <td>Name:</td> <td><%#Container.DataItem("surname")%></td> </tr> <tr> <td>Telephone:</td> <td><%#Container.DataItem("telephone")%></td> </tr> <tr> <td>Fax:</td> <td><%#Container.DataItem("fax")%></td> </tr> <tr> <td>Email:</td> <td><%#Container.DataItem("email")%></td> </tr> </table> </ItemTemplate> <SeparatorTemplate><br /><hr /><br /></SeparatorTemplate> </asp:Repeater> When I insert this usercontrol into default.aspx with this code: <%@ Register src="Modules/Content.ascx" tagname="Content" tagprefix="uc1" %> and <form id="form1" runat="server"> <div> <uc1:Content ID="Content" runat="server" /> </div> </form> I do not get any error messages but the expected content from the database is not displayed. Can someone please show me the syntax to get this working or point out where I am going wrong? Thanks in advance!

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  • ASP.net Repeater Control Problem (nothing outputted from datasource(sqldatareader))

    - by Phil
    I have the following code to get the repeaters' data in my usercontrol (content.ascx.vb): If did = 0 Then s = "select etc (statement works on server)" x = New SqlCommand(s, c) x.Parameters.Add("@contentid", Data.SqlDbType.Int) x.Parameters("@contentid").Value = contentid c.Open() r = x.ExecuteReader If r.HasRows Then Contactinforepeater.DataSource = r End If c.Close() r.Close() Else s = "select etc (statement works on server)" x = New SqlCommand(s, c) x.Parameters.Add("@contentid", SqlDbType.Int) x.Parameters("@contentid").Value = contentid x.Parameters.Add("@did", SqlDbType.Int) x.Parameters("@did").Value = did c.Open() r = x.ExecuteReader If r.HasRows Then Contactinforepeater.DataSource = r c.Close() r.Close() End If End If Then I have the following repeater control markup in my usercontrol (content.ascx): <asp:Repeater ID="Contactinforepeater" runat="server"> <HeaderTemplate> <h1>Contact Information</h1> </HeaderTemplate> <ItemTemplate> <table width="50%"> <tr> <td colspan="2"><%#Container.DataItem("position")%></td> </tr> <tr> <td>Name:</td> <td><%#Container.DataItem("surname")%></td> </tr> <tr> <td>Telephone:</td> <td><%#Container.DataItem("telephone")%></td> </tr> <tr> <td>Fax:</td> <td><%#Container.DataItem("fax")%></td> </tr> <tr> <td>Email:</td> <td><%#Container.DataItem("email")%></td> </tr> </table> </ItemTemplate> <SeparatorTemplate><br /><hr /><br /></SeparatorTemplate> </asp:Repeater> When I insert this usercontrol into default.aspx with this code: <%@ Register src="Modules/Content.ascx" tagname="Content" tagprefix="uc1" %> and <form id="form1" runat="server"> <div> <uc1:Content ID="Content" runat="server" /> </div> </form> I do not get any error messages but the expected content from the database is not displayed. Can someone please show me the syntax to get this working or point out where I am going wrong? Thanks in advance!

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  • Read sms from Mobile device with .net application?

    - by nikunj
    Hello Friends, Can anyone help me? How can I read SMS from mobile with my .net application? i have a Nokia 5310 mobile phone. Can you tell me from where i can download Nokia SDK or source code or Nokia API etc? I want to make a custom application which reads SMS and at the same time sends a response to the sender's mobile number.

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  • Need help helping in converting jquery, ajax, json and asp.net

    - by Haja Mohaideen
    I am tying out this tutorial, http://www.ezzylearning.com/tutorial.aspx?tid=5869127. It works perfectly. What I am now trying to do is to host the aspx contents as html file. This html file is hosted on my wampserver which is on my laptop. The asp.net code hosted on my test server. When I try to access, I get the following error, Resource interpreted as Script but transferred with MIME type text/html: "http://201.x.x.x/testAjax/Default.aspx/AddProductToCart?callback=jQuery17103264484549872577_1346923699990&{%20pID:%20%226765%22,%20qty:%20%22100%22,%20lblType:%20%2220%22%20}&_=1346923704482". jquery.min.js:4 Uncaught SyntaxError: Unexpected token < I am not sure how to solve this problem. index.html code $(function () { $('#btnAddToCart').click(function () { var result = $.ajax({ type: "POST", url: "http://202.161.45.124/testAjax/Default.aspx/AddProductToCart", crossDomain: true, data: '{ pID: "6765", qty: "100", lblType: "20" }', contentType: "application/json; charset=utf-8", dataType: "jsonp", success: succeeded, failure: function (msg) { alert(msg); }, error: function (xhr, err) { alert(err); } }); }); }); function succeeded(msg) { alert(msg.d); } function btnAddToCart_onclick() { } </script> </head> <body> <form name="form1" method="post"> <div> <input type="button" id="btnAddToCart" onclick="return btnAddToCart_onclick()" value="Button" /> </div> </form> aspx.vb Imports System.Web.Services Imports System.Web.Script.Services <ScriptService()> Public Class WebForm1 Inherits Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Session("test") = "" End Sub <WebMethod()> <ScriptMethod(UseHttpGet:=False, ResponseFormat:=ResponseFormat.Json)> Public Shared Function AddProductToCart(pID As String, qty As String, lblType As String) As String Dim selectedProduct As String = String.Format("+ {0} - {1} - {2}", pID, qty, lblType) HttpContext.Current.Session("test") += selectedProduct Return HttpContext.Current.Session("test").ToString() End Function End Class

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  • A good UI design for rating in .Net

    - by Ben
    Hi, im trying to add a "rating" system to an existing form (i.e 1 star, 2 Star or poor, average,good,excellent etc). Does anyone know of a way to achieve this that is aesthetically pleasing with good UX either in .Net or a free 3rd party control? Thanks

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  • how to close a sqlconnection in asp.net

    - by stighy
    Hi guys, i would like to know if there's something wrong in this asp.net code: mydatareader = mycmd.executeReader() if myDataReader.HasRow then // Do something end if myConnection.Close() If i avoid to call a "MyDataReader.Close()" does the connection close anyway ? I ask this because i'm assuming that if call a "MyConn.Close" it automatically close the associated datareader... or am i wrong ? Thanks

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  • Crystal Reports Reportviewer - Set Datasource Dynamically Not Working :argh:

    - by Albert
    I'm running CR XI, and accessing .RPT files through a ReportViewer in my ASP.NET pages. I've already got the following code, which is supposed to set the Report Datasource dynamically. rptSP = New ReportDocument Dim rptPath As String = Request.QueryString("report") rptSP.Load(rptPath.ToString, 0) Dim SConn As New System.Data.SqlClient.SqlConnectionStringBuilder(ConfigurationManager.ConnectionStrings("MyConnectionString").ConnectionString) rptSP.DataSourceConnections(SConn.DataSource, SConn.InitialCatalog).SetConnection(SConn.DataSource, SConn.InitialCatalog, SConn.UserID, SConn.Password) Dim myConnectionInfo As ConnectionInfo = New ConnectionInfo myConnectionInfo.ServerName = SConn.DataSource myConnectionInfo.DatabaseName = SConn.InitialCatalog myConnectionInfo.UserID = SConn.UserID myConnectionInfo.Password = SConn.Password 'Two new methods to loop through all objects and tables contained in the requested report and set 'login credentials for each object and table. SetDBLogonForReport(myConnectionInfo, rptSP) SetDBLogonForSubreports(myConnectionInfo, rptSP) Me.CrystalReportViewer1.ReportSource = rptSP But when I go into each .RPT file, and open up the Database Expert section, there is obviously still servernames hardcoded in there, and the code listed above doesn't seem to be able to change the servernames that are hardcoded there. I say this because I have training and production environments. When the .RPT file is hardcoded with my production server, and I open it on my training server with the code above (and the web.config has the training server in the connection string), I get the ol: Object reference not set to an instance of an object. And then if I go into the .RPT file, and change over the datasource to the training server, and try to open it again, it works fine. Why doesn't the code above overwrite the .RPT files datasource? How can I avoid having to open up each .RPT and change the datasource when migrating reports from server to server? Is there a setting in the .RPT file I'm missing or something?

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  • Unit tests and Test Runner problems under .Net 4.0

    - by Brett Rigby
    Hi there, We're trying to migrate a .Net 3.5 solution into .Net 4.0, but are experiencing complications with the testing frameworks that can operate using an assembly that is built using version 4.0 of the .Net Framework. Previously, we used NUnit 2.4.3.0 and NCover 1.5.8.0 within our NAnt scripts, but NUnit 2.4.3.0 doesn't like .Net 4.0 projects. So, we upgraded to a newer version of the NUnit framework within the test project itself, but then found that NCover 1.5.8.0 doesn't support this version of NUnit. We get errors in the code saying words to the effect of the assembly was built using a newer version of the .Net Framework than is currently in use, as it's using .Net Framework 2.0 to run the tools. We then tried using Gallio's Icarus test runner GUI, but found that this and MbUnit only support up to version 3.5 of the .Net Frameword and the result is "the tests will be ignored". In terms of the coverage side of things (for reporting into CruiseControl.net), we have found that PartCover is a good candidate for substituting-out NCover, (as the newer version of NCover is quite dear, and PartCover is free), but this is a few steps down the line yet, as we can't get the test runners to work first!! Can any shed any light on a testnig framework that will run under .Net 4.0 in the same way as I've described above? If not, I fear we may have to revert back to using .Net 3.5 until the manufacturers of the tooling that we're currently using have a chance to upgrade to .Net 4.0. Thanks.

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  • Daily tech links for .net and related technologies - Mar 26-28, 2010

    - by SanjeevAgarwal
    Daily tech links for .net and related technologies - Mar 26-28, 2010 Web Development Creating Rich View Components in ASP.NET MVC - manzurrashid Diagnosing ASP.NET MVC Problems - Brad Wilson Templated Helpers & Custom Model Binders in ASP.NET MVC 2 - gshackles The jQuery Templating Plugin and Why You Should Be Excited! - Chris Love Web Deployment Made Awesome: If You're Using XCopy, You're Doing It Wrong - Scott Hansleman Dynamic User Specific CSS Selection at Run Time - Misfit Geek Sending email...(read more)

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  • Daily tech links for .net and related technologies - Mar 18-21, 2010

    - by SanjeevAgarwal
    Daily tech links for .net and related technologies - Mar 18-21, 2010 Web Development TDD kata for ASP.NET MVC controllers (part 2) -David Take Control Of Web Control ClientID Values in ASP.NET 4.0 - Scott Mitchell Inside the ASP.NET MVC Controller Factory - Dino Esposito Microsoft, jQuery, and Templating - stephen walther Cross Domain AJAX Request with YQL and jQuery - Jeffrey Way T4MVC Add-In to auto run template -Wayne Web Design Website Content Planning The Right Way - Kristin Wemmer Microsoft...(read more)

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  • ASP.NET 4.0- Menu control enhancement.

    - by Jalpesh P. Vadgama
    Till asp.net 3.5 asp.net menu control was rendered through table. And we all know that it is very hard to have CSS applied to table. For a professional look of our website a CSS is must required thing. But in asp.net 4.0 Menu control is table less it will loaded with UL and LI tags which is easier to manage through CSS. Another problem with table is it will create a large html which will increase your asp.net page KB and decrease your performance. While with UL and LI Tags its very easy very short. So You page KB Size will also be down. Let’s take a simple example. Let’s Create a menu control in asp.net with four menu item like following. <asp:Menu ID="myCustomMenu" runat="server" > <Items> <asp:MenuItem Text="Menu1" Value="Menu1"></asp:MenuItem> <asp:MenuItem Text="Menu2" Value="Menu2"></asp:MenuItem> <asp:MenuItem Text="Menu3" Value="Menu3"></asp:MenuItem> <asp:MenuItem Text="Menu4" Value="Menu4"></asp:MenuItem> </Items></asp:Menu> It will render menu in browser like following. Now If we render this menu control with tables then HTML as you can see via view page source like following.   Now If in asp.net 4.0 It will be loaded with UL and LI tags and if you now see page source then it will look like following. Which will have must lesser HTML then it was earlier like following. So isn’t that great performance enhancement?.. It’s very cool. If you still like old way doing with tables then in asp.net 4.0 there is property called ‘RenderingMode’ is given. So you can set RenderingMode=Table then it will load menu control with table otherwise it will load menu control with UL and LI Tags. That’s it..Stay tuned for more..Happy programming.. Technorati Tags: Menu,Asp.NET 4.0

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  • A few announcements for those in the UK

    - by ScottGu
    This a quick post to announce a few upcoming events for those in the UK. I’ll be presenting in Glasgow, Scotland on March 25th I’m doing a free 5 hour presentation in Glasgow on March 25th. I’ll be covering VS 2010, ASP.NET 4, ASP.NET Web Forms 4, ASP.NET MVC 2, Silverlight and potentially show off a few new things that haven’t been announced yet. You can learn more about the event and register for free here.  There are only a few spots left – so register quickly.  When the event fills up there will be a wait-list – please add yourself to this as we’ll be encouraging people who won’t be able to attend to let us know ahead of time so that we can add more people to the event. I’ll be presenting in Birmingham, England on March 26th I’m doing a free 5 hour presentation in Birmingham (UK) on March 26th. I’ll be covering VS 2010, ASP.NET 4, ASP.NET Web Forms 4, ASP.NET MVC 2, Silverlight and also potentially show off a few new things that haven’t been announced yet. You can learn more about the event and register for free here. The event unfortunately filled up immediately (even before I had a chance to blog it) – but there is a waitlist.  If you’d like to attend please add yourself to it as hopefully a number of people will be able to attend off of it. UK Party at MIX If you are going to MIX and are from the UK send mail to [email protected] (or tweet him @plip) for an invite to a party being organized for UK MIX attendees next Sunday (March 14th).  Knowing the people involved I’m sure the party will be fun. <g> Hope this helps, Scott

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  • SharePoint Apps and Windows Azure

    - by ScottGu
    Last Monday I had an opportunity to present as part of the keynote of this year’s SharePoint Conference.  My segment of the keynote covered the new SharePoint Cloud App Model we are introducing as part of the upcoming SharePoint 2013 and Office 365 releases.  This new app model for SharePoint is additive to the full trust solutions developers write today, and is built around three core tenants: Simplifying the development model and making it consistent between the on-premises version of SharePoint and SharePoint Online provided with Office 365. Making the execution model loosely coupled – and enabling developers to build apps and write code that can run outside of the core SharePoint service. This makes it easy to deploy SharePoint apps using Windows Azure, and avoid having to worry about breaking SharePoint and the apps within it when something is upgraded.  This new loosely coupled model also enables developers to write SharePoint applications that can leverage the full capabilities of the .NET Framework – including ASP.NET Web Forms 4.5, ASP.NET MVC 4, ASP.NET Web API, EF 5, Async, and more. Implementing this loosely coupled model using standard web protocols – like OAuth, JSON, and REST APIs – that enable developers to re-use skills and tools, and easily integrate SharePoint with Web and Mobile application architectures. A video of my talk + demos is now available to watch online: In the talk I walked through building an app from scratch – it showed off how easy it is to build solutions using new SharePoint application, and highlighted a web + workflow + mobile scenario that integrates SharePoint with code hosted on Windows Azure (all built using Visual Studio 2012 and ASP.NET 4.5 – including MVC and Web API). The new SharePoint Cloud App Model is something that I think is pretty exciting, and it is going to make it a lot easier to build SharePoint apps using the full power of both Windows Azure and the .NET Framework.  Using Windows Azure to easily extend SaaS based solutions like Office 365 is also a really natural fit and one that is going to offer a bunch of great developer opportunities.  Hope this helps, Scott  P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Aplicações do SharePoint e Windows Azure

    - by Leniel Macaferi
    Segunda-feira passada eu tive a oportunidade de me apresentar dando uma palestra na SharePoint Conference (em Inglês). Meu segmento na palestra cobriu o novo modelo de Aplicações para Nuvem do SharePoint (SharePoint Cloud App Model) que estamos introduzindo como parte dos próximos lançamentos do SharePoint 2013 e Office 365. Este novo modelo de aplicações para o SharePoint é aditivo para as soluções de total confiança que os desenvolvedores escrevem atualmente, e é construído em torno de três pilares principais: Simplificar o modelo de desenvolvimento tornando-o consistente entre a versão local do SharePoint e a versão online do SharePoint fornecida com o Office 365. Tornar o modelo de execução flexível - permitindo que os desenvolvedores criem aplicações e escrevam código que pode ser executado fora do núcleo do serviço do SharePoint. Isto torna mais fácil implantar aplicações SharePoint usando a Windows Azure, evitando a preocupação com a quebra do SharePoint e das aplicações que rodam dentro dele quando algo é atualizado. Este novo modelo flexível também permite que os desenvolvedores escrevam aplicações do SharePoint que podem alavancar as capacidades do .NET Framework - incluindo ASP.NET Web Forms 4.5, ASP.NET MVC 4, ASP.NET Web API, Entity Framework 5, Async, e mais. Implementar este modelo flexível utilizando protocolos padrão da web - como OAuth, JSON e APIs REST - que permitem aos desenvolvedores reutilizar habilidades e ferramentas, facilmente integrando o SharePoint com arquiteturas Web e arquiteturas para aplicações móveis. Um vídeo da minha palestra + demos está disponível para assistir on-line (em Inglês): Na palestra eu mostrei como construir uma aplicação a partir do zero - ela mostrou como é fácil construir soluções usando a nova aplicação SharePoint, e destacou um cenário web + workflow + móvel que integra o SharePoint com código hospedado na Windows Azure (totalmente construído usando o Visual Studio 2012 e ASP.NET 4.5 - incluindo MVC e Web API). O novo Modelo de Aplicações para Nuvem do SharePoint é algo que eu acho extremamente emocionante, e que vai tornar muito mais fácil criar aplicações SharePoint usando todo o poder da Windows Azure e do .NET Framework. Usar a Windows Azure para estender facilmente soluções baseadas em SaaS como o Office 365 é também algo muito natural e que vai oferecer um monte de ótimas oportunidades para os desenvolvedores.  Espero que ajude, - Scott P.S. Além do blog, eu também estou utilizando o Twitter para atualizações rápidas e para compartilhar links. Siga-me em: twitter.com/ScottGu Texto traduzido do post original por Leniel Macaferi.

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  • Code that Worked with MultiView fails with Wizard ASP.NET

    - by davemackey
    I originally created a process that occurred by transitioning between views in a multiview and it worked fine. Now, I've moved this same code into a ASP.NET Wizard and it keeps throwing an error at the second step. The error is: Method 'System.Object AndObject(System.Object, System.Object)' has no supported translation to SQL. Any ideas why this would occur when moving the code into the wizard? I'm sure its something stupid, but I've checked over the code 3-4 times now and it appears identical operationally. Here is the code: ' Make sure we have the LDAP portion of the .NET Framework available. Imports System.DirectoryServices ' Allows us to interface with LDAP. Imports System.Data.Linq.SqlClient ' Allows us to use LINQ SQL Methods. Partial Public Class buildit Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load ' ******* Grab the LDAP info. for current user. Dim ID As FormsIdentity = DirectCast(User.Identity, FormsIdentity) Dim ticket As FormsAuthenticationTicket = ID.Ticket Dim adDirectory As New DirectoryEntry("LDAP://OU=[info],DC=[info],DC=[info],DC=[info]") ' We need to strip off @email.address from the ticket name, so we'll use substring to grab the first ' five characters. Dim adTicketID As String = ticket.Name.Substring(0, 5) Dim adEmployeeID As String adEmployeeID = adDirectory.Children.Find("CN=" & adTicketID).Properties("employeeID").Value ' ******* Lets make sure they have signed the housing contract and the community covenant. Dim dbContractSigs As New pcRoomOccupantsDataContext Dim pcContractSigs = From p In dbContractSigs.webContractSigs _ Where p.people_id = adEmployeeID _ Select p.res_contract, p.comm_life If pcContractSigs.Count.Equals(0) Then Response.Redirect("signcontract.aspx") Else Dim cs As String = pcContractSigs.First.res_contract.ToString Dim cos As String = pcContractSigs.First.comm_life.ToString If cs = "Y" And cos = "Y" Then ' We don't need to do anything. ' We use the else statement b/c there are multiple conditions that could occur besides "N" ' that would cause us to redirect to the signature page, whereas there is only one valid response - "Y". Else ' Redirect the individual to our contracts page. Response.Redirect("signcontract.aspx") End If End If ' ******* Now lets find out what gender that individual is. Dim dbIndividual As New pcPeopleDataContext Dim pcIndividual = From p In dbIndividual.PEOPLEs _ Join d In dbIndividual.DEMOGRAPHICs On p.PEOPLE_CODE_ID Equals d.PEOPLE_CODE_ID _ Where p.PEOPLE_ID = adEmployeeID _ Select p, d ' Make a session variable that will carry with the user throughout the session delineating gender. Session("sgender") = pcIndividual.First.d.GENDER.ToString ' Debug Code. ' Put a stop at end sub to get these values. ' Response.Write(adEmployeeID) End Sub Sub LinqDataSource1_Selecting(ByVal sender As Object, ByVal e As LinqDataSourceSelectEventArgs) ' Lets get a list of the dorms that are available for user's gender. Dim pcDorms As New pcDormsDataContext Dim selectedDorms = (From sd In pcDorms.PBU_WEB_DORMs _ Where IIf(Session("sgender").ToString = "M", sd.description = "Male", sd.description = "Female") _ Select sd.dorm_building).Distinct() e.Result = selectedDorms End Sub Public Sub Button_ItemCommand(ByVal Sender As Object, ByVal e As RepeaterCommandEventArgs) ' ******** Lets pass on the results of our query in LinqDataSource1_Selecting. Session("sdorm") = RTrim(e.CommandName) ' ******** Debug code. ' Response.Write(sDorm) End Sub Sub LinqDataSource2_Selecting(ByVal sender As Object, ByVal e As LinqDataSourceSelectEventArgs) ' ******** Get a list of rooms available in the dorm for user's gender. Dim pcDorms As New pcDormsDataContext Dim selectedDorm = (From sd In pcDorms.PBU_WEB_DORMs _ Where IIf(Session("sgender").ToString = "M", sd.description = "Male", sd.description = "Female") _ And sd.dorm_building = CStr(Session("sdorm")) _ Select sd.dorm_room) e.Result = selectedDorm End Sub Public Sub Button2_ItemCommand(ByVal Sender As Object, ByVal e As RepeaterCommandEventArgs) ' ******** Lets pass on the results of our query in LinqDataSource2_Selecting. Session("sroom") = RTrim(e.CommandName) End Sub Sub LinqDataSource3_Selecting(ByVal sender As Object, ByVal e As LinqDataSourceSelectEventArgs) ' ******** Grabs the individuals currently listed as residing in this room and displays them. Note the use of SqlMethods.Like ' for dorm_building, this is due to legacy issues where dorms sometimes have leading or trailing blank spaces. We could have ' also used Trim. Dim pcOccupants As New pcRoomOccupantsDataContext Dim roomOccupants = (From ro In pcOccupants.webResidents _ Where SqlMethods.Like(ro.dorm_building, "%" & CStr(Session("sdorm")) & "%") _ And ro.dorm_room = CStr(Session("sroom")) _ Select ro.person_name) e.Result = roomOccupants ' ******** Debug code. 'Response.Write(CStr(Session("sdorm"))) 'Response.Write(CStr(Session("sroom"))) End Sub Protected Sub Button4_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button4.Click ' ******** Reserve the room for a student. End Sub End Class

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  • ASP.NET GZip Encoding Caveats

    - by Rick Strahl
    GZip encoding in ASP.NET is pretty easy to accomplish using the built-in GZipStream and DeflateStream classes and applying them to the Response.Filter property.  While applying GZip and Deflate behavior is pretty easy there are a few caveats that you have watch out for as I found out today for myself with an application that was throwing up some garbage data. But before looking at caveats let’s review GZip implementation for ASP.NET. ASP.NET GZip/Deflate Basics Response filters basically are applied to the Response.OutputStream and transform it as data is written to it through the ASP.NET Response object. So a Response.Write eventually gets written into the output stream which if a filter is also written through the filter stream’s interface. To perform the actual GZip (and Deflate) encoding typically used by Web pages .NET includes the GZipStream and DeflateStream stream classes which can be readily assigned to the Repsonse.OutputStream. With these two stream classes in place it’s almost trivially easy to create a couple of reusable methods that allow you to compress your HTTP output. In my standard WebUtils utility class (from the West Wind West Wind Web Toolkit) created two static utility methods – IsGZipSupported and GZipEncodePage – that check whether the client supports GZip encoding and then actually encodes the current output (note that although the method includes ‘Page’ in its name this code will work with any ASP.NET output). /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } /// <summary> /// Sets up the current page or handler to use GZip through a Response.Filter /// IMPORTANT: /// You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if (IsGZipSupported()) { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (AcceptEncoding.Contains("deflate")) { Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "deflate"); } else { Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "gzip"); } } } As you can see the actual assignment of the Filter is as simple as: Response.Filter = new DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); which applies the filter to the OutputStream. You also need to ensure that your response reflects the new GZip or Deflate encoding and ensure that any pages that are cached in Proxy servers can differentiate between pages that were encoded with the various different encodings (or no encoding). To use this utility function now is trivially easy: In any ASP.NET code that wants to compress its Response output you simply use: protected void Page_Load(object sender, EventArgs e) { WebUtils.GZipEncodePage(); Entry = WebLogFactory.GetEntry(); var entries = Entry.GetLastEntries(App.Configuration.ShowEntryCount, "pk,Title,SafeTitle,Body,Entered,Feedback,Location,ShowTopAd", "TEntries"); if (entries == null) throw new ApplicationException("Couldn't load WebLog Entries: " + Entry.ErrorMessage); this.repEntries.DataSource = entries; this.repEntries.DataBind(); } Here I use an ASP.NET page, but the above WebUtils.GZipEncode() method call will work in any ASP.NET application type including HTTP Handlers. The only requirement is that the filter needs to be applied before any other output is sent to the OutputStream. For example, in my CallbackHandler service implementation by default output over a certain size is GZip encoded. The output that is generated is JSON or XML and if the output is over 5k in size I apply WebUtils.GZipEncode(): if (sbOutput.Length > GZIP_ENCODE_TRESHOLD) WebUtils.GZipEncodePage(); Response.ContentType = ControlResources.STR_JsonContentType; HttpContext.Current.Response.Write(sbOutput.ToString()); Ok, so you probably get the idea: Encoding GZip/Deflate content is pretty easy. Hold on there Hoss –Watch your Caching Or is it? There are a few caveats that you need to watch out for when dealing with GZip content. The fist issue is that you need to deal with the fact that some clients don’t support GZip or Deflate content. Most modern browsers support it, but if you have a programmatic Http client accessing your content GZip/Deflate support is by no means guaranteed. For example, WinInet Http clients don’t support GZip out of the box – it has to be explicitly implemented. Other low level HTTP clients on other platforms too don’t support GZip out of the box. The problem is that your application, your Web Server and Proxy Servers on the Internet might be caching your generated content. If you return content with GZip once and then again without, either caching is not applied or worse the wrong type of content is returned back to the client from a cache or proxy. The result is an unreadable response for *some clients* which is also very hard to debug and fix once in production. You already saw the issue of Proxy servers addressed in the GZipEncodePage() function: // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); This ensures that any Proxy servers also check for the Content-Encoding HTTP Header to cache their content – not just the URL. The same thing applies if you do OutputCaching in your own ASP.NET code. If you generate output for GZip on an OutputCached page the GZipped content will be cached (either by ASP.NET’s cache or in some cases by the IIS Kernel Cache). But what if the next client doesn’t support GZip? She’ll get served a cached GZip page that won’t decode and she’ll get a page full of garbage. Wholly undesirable. To fix this you need to add some custom OutputCache rules by way of the GetVaryByCustom() HttpApplication method in your global_ASAX file: public override string GetVaryByCustomString(HttpContext context, string custom) { // Override Caching for compression if (custom == "GZIP") { string acceptEncoding = HttpContext.Current.Response.Headers["Content-Encoding"]; if (string.IsNullOrEmpty(acceptEncoding)) return ""; else if (acceptEncoding.Contains("gzip")) return "GZIP"; else if (acceptEncoding.Contains("deflate")) return "DEFLATE"; return ""; } return base.GetVaryByCustomString(context, custom); } In a page that use Output caching you then specify: <%@ OutputCache Duration="180" VaryByParam="none" VaryByCustom="GZIP" %> To use that custom rule. It’s all Fun and Games until ASP.NET throws an Error Ok, so you’re up and running with GZip, you have your caching squared away and your pages that you are applying it to are jamming along. Then BOOM, something strange happens and you get a lovely garbled page that look like this: Lovely isn’t it? What’s happened here is that I have WebUtils.GZipEncode() applied to my page, but there’s an error in the page. The error falls back to the ASP.NET error handler and the error handler removes all existing output (good) and removes all the custom HTTP headers I’ve set manually (usually good, but very bad here). Since I applied the Response.Filter (via GZipEncode) the output is now GZip encoded, but ASP.NET has removed my Content-Encoding header, so the browser receives the GZip encoded content without a notification that it is encoded as GZip. The result is binary output. Here’s what Fiddler says about the raw HTTP header output when an error occurs when GZip encoding was applied: HTTP/1.1 500 Internal Server Error Cache-Control: private Content-Type: text/html; charset=utf-8 Date: Sat, 30 Apr 2011 22:21:08 GMT Content-Length: 2138 Connection: close ?`I?%&/m?{J?J??t??` … binary output striped here Notice: no Content-Encoding header and that’s why we’re seeing this garbage. ASP.NET has stripped the Content-Encoding header but left our filter intact. So how do we fix this? In my applications I typically have a global Application_Error handler set up and in this case I’ve been using that. One thing that you can do in the Application_Error handler is explicitly clear out the Response.Filter and set it to null at the top: protected void Application_Error(object sender, EventArgs e) { // Remove any special filtering especially GZip filtering Response.Filter = null; … } And voila I get my Yellow Screen of Death or my custom generated error output back via uncompressed content. BTW, the same is true for Page level errors handled in Page_Error or ASP.NET MVC Error handling methods in a controller. Another and possibly even better solution is to check whether a filter is attached just before the headers are sent to the client as pointed out by Adam Schroeder in the comments: protected void Application_PreSendRequestHeaders() { // ensure that if GZip/Deflate Encoding is applied that headers are set // also works when error occurs if filters are still active HttpResponse response = HttpContext.Current.Response; if (response.Filter is GZipStream && response.Headers["Content-encoding"] != "gzip") response.AppendHeader("Content-encoding", "gzip"); else if (response.Filter is DeflateStream && response.Headers["Content-encoding"] != "deflate") response.AppendHeader("Content-encoding", "deflate"); } This uses the Application_PreSendRequestHeaders() pipeline event to check for compression encoding in a filter and adjusts the content accordingly. This is actually a better solution since this is generic – it’ll work regardless of how the content is cleaned up. For example, an error Response.Redirect() or short error display might get changed and the filter not cleared and this code actually handles that. Sweet, thanks Adam. It’s unfortunate that ASP.NET doesn’t natively clear out Response.Filters when an error occurs just as it clears the Response and Headers. I can’t see where leaving a Filter in place in an error situation would make any sense, but hey - this is what it is and it’s easy enough to fix as long as you know where to look. Riiiight! IIS and GZip I should also mention that IIS 7 includes good support for compression natively. If you can defer encoding to let IIS perform it for you rather than doing it in your code by all means you should do it! Especially any static or semi-dynamic content that can be made static should be using IIS built-in compression. Dynamic caching is also supported but is a bit more tricky to judge in terms of performance and footprint. John Forsyth has a great article on the benefits and drawbacks of IIS 7 compression which gives some detailed performance comparisons and impact reviews. I’ll post another entry next with some more info on IIS compression since information on it seems to be a bit hard to come by. Related Content Built-in GZip/Deflate Compression in IIS 7.x HttpWebRequest and GZip Responses © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET   IIS7  

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  • Back to Basics: When does a .NET Assembly Dependency get loaded

    - by Rick Strahl
    When we work on typical day to day applications, it's easy to forget some of the core features of the .NET framework. For me personally it's been a long time since I've learned about some of the underlying CLR system level services even though I rely on them on a daily basis. I often think only about high level application constructs and/or high level framework functionality, but the low level stuff is often just taken for granted. Over the last week at DevConnections I had all sorts of low level discussions with other developers about the inner workings of this or that technology (especially in light of my Low Level ASP.NET Architecture talk and the Razor Hosting talk). One topic that came up a couple of times and ended up a point of confusion even amongst some seasoned developers (including some folks from Microsoft <snicker>) is when assemblies actually load into a .NET process. There are a number of different ways that assemblies are loaded in .NET. When you create a typical project assemblies usually come from: The Assembly reference list of the top level 'executable' project The Assembly references of referenced projects Dynamically loaded at runtime via AppDomain/Reflection loading In addition .NET automatically loads mscorlib (most of the System namespace) the boot process that hosts the .NET runtime in EXE apps, or some other kind of runtime hosting environment (runtime hosting in servers like IIS, SQL Server or COM Interop). In hosting environments the runtime host may also pre-load a bunch of assemblies on its own (for example the ASP.NET host requires all sorts of assemblies just to run itself, before ever routing into your user specific code). Assembly Loading The most obvious source of loaded assemblies is the top level application's assembly reference list. You can add assembly references to a top level application and those assembly references are then available to the application. In a nutshell, referenced assemblies are not immediately loaded - they are loaded on the fly as needed. So regardless of whether you have an assembly reference in a top level project, or a dependent assembly assemblies typically load on an as needed basis, unless explicitly loaded by user code. The same is true of dependent assemblies. To check this out I ran a simple test: I have a utility assembly Westwind.Utilities which is a general purpose library that can work in any type of project. Due to a couple of small requirements for encoding and a logging piece that allows logging Web content (dependency on HttpContext.Current) this utility library has a dependency on System.Web. Now System.Web is a pretty large assembly and generally you'd want to avoid adding it to a non-Web project if it can be helped. So I created a Console Application that loads my utility library: You can see that the top level Console app a reference to Westwind.Utilities and System.Data (beyond the core .NET libs). The Westwind.Utilities project on the other hand has quite a few dependencies including System.Web. I then add a main program that accesses only a simple utillity method in the Westwind.Utilities library that doesn't require any of the classes that access System.Web: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); } StringUtils.NewStringId() calls into Westwind.Utilities, but it doesn't rely on System.Web. Any guesses what the assembly list looks like when I stop the code on the ReadLine() command? I'll wait here while you think about it… … … So, when I stop on ReadLine() and then fire up Process Explorer and check the assembly list I get: We can see here that .NET has not actually loaded any of the dependencies of the Westwind.Utilities assembly. Also not loaded is the top level System.Data reference even though it's in the dependent assembly list of the top level project. Since this particular function I called only uses core System functionality (contained in mscorlib) there's in fact nothing else loaded beyond the main application and my Westwind.Utilities assembly that contains the method accessed. None of the dependencies of Westwind.Utilities loaded. If you were to open the assembly in a disassembler like Reflector or ILSpy, you would however see all the compiled in dependencies. The referenced assemblies are in the dependency list and they are loadable, but they are not immediately loaded by the application. In other words the C# compiler and .NET linker are smart enough to figure out the dependencies based on the code that actually is referenced from your application and any dependencies cascading down into the dependencies from your top level application into the referenced assemblies. In the example above the usage requirement is pretty obvious since I'm only calling a single static method and then exiting the app, but in more complex applications these dependency relationships become very complicated - however it's all taken care of by the compiler and linker figuring out what types and members are actually referenced and including only those assemblies that are in fact referenced in your code or required by any of your dependencies. The good news here is: That if you are referencing an assembly that has a dependency on something like System.Web in a few places that are not actually accessed by any of your code or any dependent assembly code that you are calling, that assembly is never loaded into memory! Some Hosting Environments pre-load Assemblies The load behavior can vary however. In Console and desktop applications we have full control over assembly loading so we see the core CLR behavior. However other environments like ASP.NET for example will preload referenced assemblies explicitly as part of the startup process - primarily to minimize load conflicts. Specifically ASP.NET pre-loads all assemblies referenced in the assembly list and the /bin folder. So in Web applications it definitely pays to minimize your top level assemblies if they are not used. Understanding when Assemblies Load To clarify and see it actually happen what I described in the first example , let's look at a couple of other scenarios. To see assemblies loading at runtime in real time lets create a utility function to print out loaded assemblies to the console: public static void PrintAssemblies() { var assemblies = AppDomain.CurrentDomain.GetAssemblies(); foreach (var assembly in assemblies) { Console.WriteLine(assembly.GetName()); } } Now let's look at the first scenario where I have class method that references internally uses System.Web. In the first scenario lets add a method to my main program like this: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); PrintAssemblies(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } UpdateFromWebRequest() internally accesses HttpContext.Current to read some information of the ASP.NET Request object so it clearly needs a reference System.Web to work. In this first example, the method that holds the calling code is never called, but exists as a static method that can potentially be called externally at some point. What do you think will happen here with the assembly loading? Will System.Web load in this example? No - it doesn't. Because the WebLogEntry() method is never called by the mainline application (or anywhere else) System.Web is not loaded. .NET dynamically loads assemblies as code that needs it is called. No code references the WebLogEntry() method and so System.Web is never loaded. Next, let's add the call to this method, which should trigger System.Web to be loaded because a dependency exists. Let's change the code to: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.WriteLine("--- Before:"); PrintAssemblies(); WebLogEntry(); Console.WriteLine("--- After:"); PrintAssemblies(); Console.ReadLine(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } Looking at the code now, when do you think System.Web will be loaded? Will the before list include it? Yup System.Web gets loaded, but only after it's actually referenced. In fact, just until before the call to UpdateFromRequest() System.Web is not loaded - it only loads when the method is actually called and requires the reference in the executing code. Moral of the Story So what have we learned - or maybe remembered again? Dependent Assembly References are not pre-loaded when an application starts (by default) Dependent Assemblies that are not referenced by executing code are never loaded Dependent Assemblies are just in time loaded when first referenced in code All of this is nothing new - .NET has always worked like this. But it's good to have a refresher now and then and go through the exercise of seeing it work in action. It's not one of those things we think about everyday, and as I found out last week, I couldn't remember exactly how it worked since it's been so long since I've learned about this. And apparently I'm not the only one as several other people I had discussions with in relation to loaded assemblies also didn't recall exactly what should happen or assumed incorrectly that just having a reference automatically loads the assembly. The moral of the story for me is: Trying at all costs to eliminate an assembly reference from a component is not quite as important as it's often made out to be. For example, the Westwind.Utilities module described above has a logging component, including a Web specific logging entry that supports pulling information from the active HTTP Context. Adding that feature requires a reference to System.Web. Should I worry about this in the scope of this library? Probably not, because if I don't use that one class of nearly a hundred, System.Web never gets pulled into the parent process. IOW, System.Web only loads when I use that specific feature and if I am, well I clearly have to be running in a Web environment anyway to use it realistically. The alternative would be considerably uglier: Pulling out the WebLogEntry class and sticking it into another assembly and breaking up the logging code. In this case - definitely not worth it. So, .NET definitely goes through some pretty nifty optimizations to ensure that it loads only what it needs and in most cases you can just rely on .NET to do the right thing. Sometimes though assembly loading can go wrong (especially when signed and versioned local assemblies are involved), but that's subject for a whole other post…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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