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SQL server processes hanging around after applet exits

3 posts in JDBC Connect (product renamed to JConnect) Last posting was on 1997-09-23 14:56:52.0Z
Michel van der List Posted on 1997-09-17 16:24:54.0Z
Message-ID: <34200456.167E@sbphrd.com>
Date: Wed, 17 Sep 1997 12:24:54 -0400
From: Michel van der List <vanderlistmj@sbphrd.com>
Organization: SmithKline Beecham Pharmaceuticals R & D, Bioinformatics
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Subject: SQL server processes hanging around after applet exits
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I have been using jConnect (ebf 7426) for a while now. I am using
Symantec Cafe on NT 4.0 as our Java development platform. I have
noticed that during our debugging sessions, processes on the SQL
server do not go away, even when the applet I am debugging has
ceased to exist. The timeout parameter for the connection is set
to 60.

When stopping the cascade server, the processes immediately
disappears from the SQL server.

The questions I have are:

- Am I missing something?
- If not, why are these processes hanging around?
- Is there any way to debug (or at least log) some of the TDS stuff
in the Cascade server?

Michel

-------------------------------------------------------------------
Michel van der List SmithKline Beecham Pharmaceuticals R & D
vanderlistmj@sbphrd.com UW2230, 709 Swedeland Road, P.O. Box 1539
(610) 270-4525 King of Prussia, PA 19406-0939


David Clegg Posted on 1997-09-18 18:20:04.0Z
Message-ID: <342170D4.6D4E9B69@sybase.com>
Date: Thu, 18 Sep 1997 11:20:04 -0700
From: David Clegg <davec@sybase.com>
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To: Michel van der List <vanderlistmj@sbphrd.com>
Subject: Re: SQL server processes hanging around after applet exits
References: <34200456.167E@sbphrd.com>
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Michel van der List wrote:
>
> I have been using jConnect (ebf 7426) for a while now. I am using
> Symantec Cafe on NT 4.0 as our Java development platform. I have
> noticed that during our debugging sessions, processes on the SQL
> server do not go away, even when the applet I am debugging has
> ceased to exist. The timeout parameter for the connection is set
> to 60.

I assume that you mean that you have set
DriverManager.setLoginTimeout(60);
before connecting? This only affects how long the jConnect driver
will wait during login for the server to respond -- has nothing to
do with how long an idle connection remains open.

>
> When stopping the cascade server, the processes immediately
> disappears from the SQL server.
>
> The questions I have are:
>
> - Am I missing something?
The Cascade server doesn't close its connection to the SQL Server
until the connection from the client is closed. Apparently that
connection is NOT being closed. You should make sure that your
Applet has a stop() method implemented -- and that it closes your
connection.
Be aware that the stop method is called whenever the page your
applet is on leaves the "current" frame in your browser. It would
be unfortunate for your connection to be closed and the application
screwed up just because the user popped up/down to another page.

There is a pretty good whitepaper on this available from netscape:

http://developer.netscape.com/library/technote/java/appletlife.html

> - If not, why are these processes hanging around?
> - Is there any way to debug (or at least log) some of the TDS stuff
> in the Cascade server?
Not yet, not with that server. I've got support for this sort of
capability on the 2nd tier list of features for the 3.0 release --
hope to get to it, but it didn't make the "high" priority list
when I shopped this stuff around a few months ago.

BTW. The jConnect3.0 Beta product will soon be upgraded to support
a new form of HTTP tunnelling. I'm planning to End-Of-Life the
Cascade server/gateway -- it isn't a bad little application but
it was never intended to be a "robust" solution for real deployment.

The replacement will be a published HTTP/Tds tunnelling protocol which
can be implemented in a variety of ways (CGI-script, NSAPI, ISAPI, etc.)
and we will be delivering source code + compiled classes that you
can use as a Servlet in a JavaServer (or any other server that supports
the javax.servlet.* framework).

With this new form of gateway, you can configure an "Idle-timeout"
on the gateway and on a per-connection bases from your application.
If the connection is idle for more than the specified amount of time,
the server closes the connection. If the application ever does
wake up and try to resume, it will get an SQLException indicating
that the session was timed out.

Besides this timeout feature, and allowing use of more "standard"
web servers, this should also allow you to tunnel through ANY firewall
(I believe that all firewalls support HTTP!), and if you configure
the Servlet to run on an HTTPS port, then you can get SSL-Encryption
and mutual authentication to the gateway. If your gateway is
safely inside your firewall then the clear-text TDS between your
gateway and your SQL-Servers will be of much less security concern
than sending username/password/bank-records/medical-records over
the internet from your browser!

I will be very interested in anyone's feedback on this:
Concerns about security/safety,
Administrative problems,
Performance,
Requirements for support for other server frameworks:
(Netscape/MS/Apache)

dave

>
> Michel
>
> -------------------------------------------------------------------
> Michel van der List SmithKline Beecham Pharmaceuticals R & D
> vanderlistmj@sbphrd.com UW2230, 709 Swedeland Road, P.O. Box 1539
> (610) 270-4525 King of Prussia, PA 19406-0939


Ben Cotton Posted on 1997-09-23 14:56:52.0Z
Message-ID: <3427D8B4.F83A60A5@bear.com>
Date: Tue, 23 Sep 1997 10:56:52 -0400
From: Ben Cotton <bcotton@bear.com>
Organization: Bear Stearns & Co.
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To: David Clegg <davec@sybase.com>
Subject: Re: SQL server processes hanging around after applet exits
References: <34200456.167E@sbphrd.com> <342170D4.6D4E9B69@sybase.com>
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David Clegg wrote:
>
[...]
> BTW. The jConnect3.0 Beta product will soon be upgraded to support
> a new form of HTTP tunnelling. I'm planning to End-Of-Life the
> Cascade server/gateway -- it isn't a bad little application but
> it was never intended to be a "robust" solution for real deployment.
>
> The replacement will be a published HTTP/Tds tunnelling protocol which
> can be implemented in a variety of ways (CGI-script, NSAPI, ISAPI, etc.)
> and we will be delivering source code + compiled classes that you
> can use as a Servlet in a JavaServer (or any other server that supports
> the javax.servlet.* framework).
[...]
> I will be very interested in anyone's feedback on this:
> Concerns about security/safety,
> Administrative problems,
> Performance,
> Requirements for support for other server frameworks:
> (Netscape/MS/Apache)
>
> dave

Hi Dave,

Be sure to yell loud and clear my way when you guys make available the
servlet-centric bundle you mention above. I'd definitely be interested
in checking it out and promise abundant feedback.

-Ben