c# - How to allow SQL Server database connection from an ASP.NET web app and a Windows service? -

i have asp.net web application , windows service running on same server machine. both need connect same database, using following code:

using (sqlconnection cn = new sqlconnection(strdbconnect)) {     cn.open();      //and on... } 

but gives me exception when try connect service:

"cannot open user default database. login failed.\r\nlogin failed user 'nt authority\system'."

the connection string i'm using both is, may different on actual deployment server:

data source=.\sqlexpress;integrated security=sspi;attachdbfilename='c:\users\user\databases\app_data\database1.mdf';user instance=true;connection timeout=15

so i'm assuming need add sharing parameter connection string. question is, how ensure more 1 process can connect sql server database?

create specific user.

use user identity of app pool

use user identity service.

add user sql server necessary rights.