如何在Threaded .Net Webservice中啓用會話？

Question

我有一個NET Web服務用2種以下方法：

[WebMethod(EnableSession = true)] 
public void A() 
{ 
    HttpSessionState session = Session; 

    Thread thread = new Thread(B); 
    thread.Start(); 
} 

[WebMethod(EnableSession = true)] 
public void B() 
{ 
    HttpSessionState session = Session; 
} 

場景1）當我直接方法調用B，會話不爲空

場景2）但是當我請致電A，B會話和HttpContext.Current都爲空。

爲什麼？如何在第二種情況下啓用B中的會話？我如何訪問A中的會話？我應該把它的會議通過B嗎？如果是的話如何？

方法B不應該有會話作爲參數。

謝謝，

Answer 1

我必須使用一個全球性的領域：

/// <summary> 
/// Holds the current session for using in threads. 
/// </summary> 
private HttpSessionState CurrentSession; 

[WebMethod(EnableSession = true)] 
public void A() 
{ 
    CurrentSession = Session; 

    Thread thread = new Thread(B); 
    thread.Start(); 
} 

[WebMethod(EnableSession = true)] 
public void B() 
{ 
    //for times that method is not called as a thread 
    CurrentSession = CurrentSession == null ? Session : CurrentSession; 

    HttpSessionState session = CurrentSession; 
} 

Answer 2

這是因爲你在一個新的線程中啓動B.

見http://forums.asp.net/t/1276840.aspx 或 http://forums.asp.net/t/1630651.aspx/1

Answer 3

[WebMethod(EnableSession = true)] 
public void A() 
{ 
    HttpSessionState session = Session; 

    Action action =() => B_Core(session); 
    Thread thread = new Thread(action); 
    thread.Start(); 
} 

[WebMethod(EnableSession = true)] 
public void B() 
{ 
    HttpSessionState session = Session; 
    B_Core(session); 
} 
private void B_Core(HttpSessionState session) 
{ 
    // todo 
}