Getting session in .NET ASMX web-service

问题

I have an ASMX webservice hosted alongside my ASP.NET web app. Now, I need to get the users session into the Webservice. To test this I made this simple method:

    [WebMethod(EnableSession = true)]
    public string checkSession()
    {
        return HttpContext.Current.Session["userid"].ToString();
    }

So, first I login to my web app, then in the browser goto my webservice and click "checkSession" on that auto generated test page. I have tested this on 3 computers. All 3 of those work fine with the webapp(so the sessions are being created etc), and 2 of those return the value of Session["userid"] on invoking the webmethod, however the last computer returns "Object reference not set to an instance of an object" because Session is null.

So, whats the difference between these computers and why can my ASP.NET app get the sessions on all computers but the webservice cant?

回答1:

maybe it's too late, but have you tried this:

[WebMethod(EnableSession = true)]
public string checkSession()
{
    return HttpContext.Current.Session.SessionID
}

回答2:

SessionIDs are stored as cookies on the client's browser by default (Session State Overview). So check if that cookie is being created properly on that problem computer. Maybe cookies are disabled for some reason? In that case it would not be sending the SessionID to the server when you are hitting that web service.

回答3:

Can you check how many worker processes is your application using? You can check it in your App pool settings in IIS.

If more than one worker process are being used then it is called to be running a web garden. If that is the case then in proc session will not be useful as this session is not shared among the worker processes. Have a look at http://www.west-wind.com/weblog/posts/2005/Apr/20/Why-you-shouldnt-use-InProc-Session-State-in-ASPNET

回答4:

Have you got Session disabled in IIS, this would over rule .net.

Have a look at this http://technet.microsoft.com/en-us/library/cc732964(v=ws.10).aspx - it tells you how to disable session, but shows where to check the setting.

Thanks Fran

回答5:

By default web services are and should be stateless. However if you must use session information be sure to use the marker interfaces IReadOnlySessionState and IRequiresSessionState in order to access, use, or modify session state information in the webservice.

回答6:

Web service by default wont support Session. You need to explicitly specify the parameter in web method attribute

These two things work for me

<add name="Session" type="System.Web.SessionState.SessionStateModule"/> under <httpModules>
enableSessionState="true" in <page> tag

回答7:

best way to do this approach check before your session is not null and in the other side you initialize the selected session with your value and then when and where web service working with httpcontext.current.session have value !

web services are stateless and best way is get value in web service instead of set or initialize session value

来源：https://stackoverflow.com/questions/3297637/getting-session-in-net-asmx-web-service

标签

ASP.NET

web-services

session-state