由於早期網站都是VB.net寫的，若是直接換成 C#，就會耗費很多時間在轉換程式上
因此 ASP.NET 特別可以在同一網站同時寫 vb 跟 C#，方式是在 web.config compilation 加上設定

    <compilation debug="true" defaultLanguage="c#" targetFramework="4.0">

     <codeSubDirectories>

        <add directoryName="VB_Code"/>

        <add directoryName="CS_Code"/>

     </codeSubDirectories>

    </compilation>

也就是 VB.NET 的 code 就放到 ~\APP_Code\VB_Code 目錄
C# 的 code 就放到 ~\APP_Code\CS_Code 目錄
這樣做有兩點要注意
1.  Namespace 的命名，最好不要互相衝突, 要能夠區分出來
2.  VB_Code 與 CS_Code 放的位置有很大的影響, 因為牽涉到 compiler的先後順序，因為 VB_Code 在 CS_Code 在前面，所以 CS_Code可以叫用 VB_Code下的程式，但是 VB_Code 卻不能叫用 CS_Code 的程式，如果希望 VB_Code可以叫用 CS_Code的程式，就把設定換過來

    <compilation debug="true" defaultLanguage="c#" targetFramework="4.0">

     <codeSubDirectories>

        <add directoryName="CS_Code"/>

<add directoryName="VB_Code"/>

     </codeSubDirectories>

    </compilation>

缺點就是反過來 CS_Code不能使用 VB_Code的程式

基本上，若是舊的程式碼都在VB_Code 那就把 VB_Code 放到前面

對於了解或設定 web.config 蠻有幫助的
http://weblogs.asp.net/jongalloway/10-things-asp-net-developers-should-know-about-web-config-inheritance-and-overrides
 

這個問題與之前 reiko 提到的狀況是一樣的
http://blog.uwinfo.com.tw/auth/article/reiko/172
基本上就是 ASP.NET 無法辨別 IE11的UserAgent， 誤判他是別種瀏覽器造成

上此 hotfix 就可以解決 
http://support.microsoft.com/kb/2836939

今天設計反應新增電子報時發生問題
 
 解決方式
1. 先確認 aspx  => ValidateRequest="false
2. 上面如果設定對 

在Web.config中<system.web>中加入

這段 <httpRuntime requestValidationMode="2.0" />就ok了!!!

造成的原因
是.NET 4.0跟2.0版本在請求驗證的定義不同：

ASP.NET Request Validation 請求驗證是ASP.NET提供來保護XSS攻擊的一項功能

在2.0 僅針對.aspx及class進行驗證…

但到了4.0，請求驗認範圍擴大到所有的請求…

而不是只有.aspx，還包含WebService呼叫以及自訂的http Handlers，都會去驗證http請求的內容…

 

假如你現在在ASP.NET 4.0 的環境下的話，就算進行上述的設定，可能仍會出現驗證失敗的訊息(潛在危險Request.QueryString的錯誤訊息)
因為ASP.NET4.0與2.0版本在請求驗證的定義上已經有所不同：

這時為了避免這樣的問題，一樣在Web.Config中 <system.web>下加入下列語句
<httpRuntime requestValidationMode="2.0" />

http://www.dotblogs.com.tw/pin0513/archive/2010/10/22/18522.aspx

問題情形：.NET 4.0在遇到IE11時，會將Style的width拿掉

參考：http://forums.asp.net/t/1934887.aspx

解決方法：安裝更新 KB2836939 下載
 

ASP.NET程式開發時，有時候會寫資料到cookies
這時我們會用 Response.Cookies.Add 寫入
但是大家都會忽略到一種情況，如果後面程式也會使用到該cookies時
Request.Cookies 會抓不到剛設定的cookies
這時就要 Request.Cookies.Set 來設定 Request 值

錯誤示範:
Page_Load --> Response.Cookies.Add a Cookie named "test"
Page_PreRender --> Request.Cookies("test") --> Nothing 

正確示範(同時寫兩行):
Page_Load --> Response.Cookies.Add a Cookie named "test"
              Request.Cookies.Set a Cookie named "test" 
Page_PreRender --> Request.Cookies("test") --> Got it!

 

 ASP.NET 在處理 HTTP POST 要求時最多只能接受 1,000 個參數，一般來說不會有人透過 POST 傳遞表單資料超過 1,000 個欄位 ( 以筆者的經驗來說，傳過最多的一次是 700 個欄位，當時是個問卷系統 )，如果傳數參數超過 1,000 筆的話，就會出現 Operation is not valid due to the current state of the object. (英文) 或 由於該物件目前的狀態，導致作業無效。 (中文) 例外狀況，細部的例外訊息會有 HttpException (0x80004005): The URL-encoded form data is not valid. (英文) 或 HttpException (0x80004005): URL 編碼型式資料無效。
參考：http://blog.miniasp.com/post/2012/01/01/Efficient-Denial-of-Service-Attacks-on-Web-Application-Platforms.aspx

解：
web.config加下面這個設定

<appSettings>

     <add key="aspnet:MaxHttpCollectionKeys" value="5000" />

</appSettings>

 

從 http://blog.ie-soft.de/post/2007/12/globalasax-events.aspx  抄來的. 留作參考

HttpApplication Events:

Application_AcquireRequestState
Occurs when ASP.NET acquires the current state (for example, session state) that is associated with the current request. 

Application_AuthenticateRequest
Occurs when a security module has established the identity of the user. 

Application_AuthorizeRequest
Occurs when a security module has verified user authorization. 

Application_BeginRequest
Occurs as the first event in the HTTP pipeline chain of execution when ASP.NET responds to a request. 

Application_Disposed
Adds an event handler to listen to the Disposed event on the application. 

Application_EndRequest
Occurs as the last event in the HTTP pipeline chain of execution when ASP.NET responds to a request. 

Application_Error
Occurs when an unhandled exception is thrown. 

Application_PostAcquireRequestState
Occurs when the request state (for example, session state) that is associated with the current request has been obtained. 

Application_PostAuthenticateRequest
Occurs when a security module has established the identity of the user. 

Application_PostAuthorizeRequest
Occurs when the user for the current request has been authorized. 

Application_PostMapRequestHandler
Occurs when ASP.NET has mapped the current request to the appropriate event handler. 

Application_PostReleaseRequestState
Occurs when ASP.NET has completed executing all request event handlers and the request state data has been stored. 

Application_PostRequestHandlerExecute
Occurs when the ASP.NET event handler (for example, a page or an XML Web service) finishes execution. 

Application_PostResolveRequestCache
Occurs when ASP.NET bypasses execution of the current event handler and allows a caching module to serve a request from the cache. 

Application_PostUpdateRequestCache
Occurs when ASP.NET completes updating caching modules and storing responses that are used to serve subsequent requests from the cache. 

Application_PreRequestHandlerExecute
Occurs just before ASP.NET begins executing an event handler (for example, a page or an XML Web service). 

Application_PreSendRequestContent
Occurs just before ASP.NET sends content to the client. 

Application_PreSendRequestHeaders
Occurs just before ASP.NET sends HTTP headers to the client. 

Application_ReleaseRequestState
Occurs after ASP.NET finishes executing all request event handlers. This event causes state modules to save the current state data. 

Application_ResolveRequestCache
Occurs when ASP.NET completes an authorization event to let the caching modules serve requests from the cache, bypassing execution of the event handler (for example, a page or an XML Web service). 

Application_UpdateRequestCache
Occurs when ASP.NET finishes executing an event handler in order to let caching modules store responses that will be used to serve subsequent requests from the cache. 

Application_Init
This method occurs after _start and is used for initializing code. 

Application_Start
As with traditional ASP, used to set up an application environment and only called when the application first starts.

Application_End
Again, like classic ASP, used to clean up variables and memory when an application ends.

Session Events:

Session_Start
As with classic ASP, this event is triggered when any new user accesses the web site.

Session_End
As with classic ASP, this event is triggered when a user's session times out or ends. Note this can be 20 mins (the default session timeout value) after the user actually leaves the site.

Profile Events:

Profile_MigrateAnonymous
Occurs when the anonymous user for a profile logs in.

Passport Events:

PassportAuthentication_OnAuthenticate
Raised during authentication. This is a Global.asax event that must be named PassportAuthentication_OnAuthenticate.
 

Possibly more events defined in other HttpModules like:

System.Web.Caching.OutputCacheModule
System.Web.SessionState.SessionStateModule
System.Web.Security.WindowsAuthentication
System.Web.Security.FormsAuthenticationModule
System.Web.Security.PassportAuthenticationModule
System.Web.Security.UrlAuthorizationModule
System.Web.Security.FileAuthorizationModule
System.Web.Profile.ProfileModule