RE: Keep Socket connection open in ATL Server (ISAPI)

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Hello Charles,

From your description, I understand you've used ATL Server project to
develop a ISAPI extension based server application. You want to make the
connection from ISAPI to server application keeped from session to
session(based on client request), however, you found the ISAPI extension
module will be unloaded periodically, correct?

Regarding on this problem, I'd like to confirm whether you've developing
the ATL server project(and test the compiled components) on XP/IIS5 or
WIN2K3 server/IIS6. Based on my experience, the ISAPI code itself doesn't
have particular settings to control its lifetime or cycle. It is the IIS
server process which control the load/unload lifecycle of those installed
ISAPI components. Normally, if the IIS site/virtual dir has choosen to
cache ISAPI extension, the extension dll will be loaded at the first
request of the corresponding service document/url, and it will be unloaded
until the hosting IIS worker process be unloaded(shutdown or recycle). Here
are two blog articles from David Wang's weblog which has included
discussion on this:

http://w3-4u.blogspot.com/2006/12/qa-on-process-threading-and-dll.html

http://blogs.msdn.com/david.wang/archive/2005/10/14/HOWTO_IIS_6_Request_Proc
essing_Basics_Part_1.aspx

For your case here, you can also monitor the hosting IIS worker process of
your extension dll(for IIS6, it is w3wp while for IIS5, it may vary depend
on the "Protection Level" of the application virtual dir) to see whether it
is because the worker process shutdown/recycle that make your ISAPI
extension dll unloaded. For IIS5, you can set your webserver application
virtual dir's "protection level" to "high" so that it is hosted in a single
separate worker process(dllhost.exe). For IIS6, you can configure your
application virtual dir to use a separate Application Pool so that it will
be hosted in a individual worker process(w3wp.exe)

#Configure Application Isolation Settings for IIS 5.0 Isolation Mode
http://technet2.microsoft.com/WindowsServer/en/library/0f18f73b-03cf-4f81-92
e2-d6ee4f248c401033.mspx?mfr=true

And for IIS6, there is a setting of Application Pool to control how long
idle time it will wait before the worker process(of that application pool)
be shutdown, you can find it in Application Pool's setting.

http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/8
3b35271-c93c-49f4-b923-7fdca6fae1cf.mspx?mfr=true

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead



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