问题
I have the following use scenario: User logs in to ASP.NET application; and at some point makes a connection to remote TCP/IP server. The server's response may come after significant delay (say, a few hours). Imagine that the user submits a batch job, and the job may be running for a long time. So, the user may close the browser, get some coffee and come back to see the results later.
However, if client closes the connection, the server will never return the results. So, keeping Socket info in Application object won't work - once user closes the browser, it goes away.
Is there any other way to persist this open socket while IIS is up? Also, if the second user logs in, I would prefer to use the same connection. Finally, I realize that the solution is brittle, and it may occasionally break. It's OK.
Remote server is 20-year old mainframe application; so no chance for changes there. And as long as the user doesn't log out - everything is working fine now. Everything is on the LAN, so there are no routing issues to complicate the situation.
回答1:
The contents of the application dictionary are not lost when a user logs out. Your scheme will work (in a brittle way, but you say that's ok).
Note, that worker processes can exit for many reasons, so expect to be killed at arbitrary points in time.
回答2:
you have several options for persisting session-state: MSDN - Session-State Modes
- inproc mode: you disconnect, state is lost. if you use cookies, and store info/data somewhere on the backend, then you can map the GUID to the data, regardless of session. or use application-state.
- stateserver: persisted across disconnects and application restarts, but not across iis/pool/server restarts, unless you use another server, or cookie/auth. can be problematic sometimes.
- sqlserver: as the name implies, uses a specially formatted db/table structure to persist state data across all sorts of scenarios.
- custom/off: allows you to build your own provider, or turns it off completely.
here's the cookie method, by far the simplest (you have to generate a GUID, then store it in the cookie and application state or a backend DB): MSDN - Maintaining Session State with Cookies
you can persist cookies on the user's client. then, on server reboot/client disconnect/any other scenario just pull the GUID from app/session state or from a backend DB, which will also store the data for the reports/output.
also, as a caution: even though cookies can be used to auth a user to an account/db record via GUID, it is considered insecure for all other purposes except unindentifiable information, such as: view shopping cart, simple reports, status, etc...
oh, and the stuff on IIS session timeouts (20 mins by default): MSDN - Configure Session Time-out (IIS 7) and MSDN - Configure Idle Time-out Settings for an Application Pool (IIS 7)
completely forgot to add the links on: ASP.NET Application State Overview, ASP.NET Session State Overview, but storing large amounts of data on a busy server in application state is not recommended. oh yea, and MSDN - Caching Application Data
来源：https://stackoverflow.com/questions/23852626/how-do-i-keep-tcp-ip-socket-open-in-iis