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+Date: Fri, 30 Nov 2001 10:14:12 +0100
+From: Laszlo Hornyak <hornyakl@freemail.hu>
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+To: pgsql-general@postgresql.org
+Subject: [GENERAL] java stored procedures
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+Hi!
+
+A few months ago I asked if anyone started working on PL/JAVA, the
+ansver was no. Now I started to write a java stored procedure language
+and environment for PostgreSQL. Some code is already working, and it is
+geting interresting. So, I would like to ask you to write me your ideas,
+suggestions, etc for this environment.
+The source code will be available under GPL when it is worth for
+distributing it (this will take for a while).
+thanks.
+
+Laszlo Hornyak
+
+
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+From pgsql-general-owner+M18182=candle.pha.pa.us=pgman@postgresql.org Tue Dec 4 13:14:09 2001
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+To: Barry Lind <barry@xythos.com>
+cc: Laszlo Hornyak <hornyakl@freemail.hu>, pgsql-general@postgresql.org,
+ pgsql-jdbc@postgresql.org
+Subject: Re: [GENERAL] java stored procedures
+References: <3C074DE4.9040905@freemail.hu> <3C0BE325.3020809@xythos.com>
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+From: Doug McNaught <doug@wireboard.com>
+Date: 04 Dec 2001 12:58:47 -0500
+In-Reply-To: Barry Lind's message of "Tue, 04 Dec 2001 08:44:50 -0800"
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+
+Barry Lind <barry@xythos.com> writes:
+
+> Having one jvm that all the postgres backend processes communicate with makes
+> the whole feature much more complicated, but is necessary in my opinion.
+
+Agreed. Also, the JVM is a multithreaded app, and running it inside a
+non-threaded program (the backend) might cause problems.
+
+> Then the question becomes how does the jvm process interact with the database
+> since they are two different processes. You will need some sort of
+> interprocess communication between the two to execute sql statements. This
+> could be accomplished by using the existing jdbc driver. But the bigest
+> problem here is getting the transaction semantics right. How does a sql
+> statement being run by a java stored procedure get access to the same
+> connection/transaction as the original client? What you don't want happening
+> is that sql issued in a stored java procedure executes in a different
+> transaction as the caller, what would rollback of the stored function call
+> mean in that case?
+
+I think you would have to to expose the SPI layer to Java running in a
+separate process, either using an RMI server written in C or a custom
+protocol over a TCP socket (Java of course can't do Unix sockets).
+This raises some thorny issues of authentication and security but I
+don't think they're insurmountable. You could, for example, create a
+cryptographically strong "cookie" in the backend when a Java function
+is called. The cookie would be passed to the Java function when it
+gets invoked, and then must be passed back to the SPI layer in order
+for the latter to accept the call. A bit clunky but should be safe as
+far as I can see.
+
+The cookie would be needed anyhow, I think, in order for the SPI layer
+to be able to find the transaction that the Java function was
+originally invoked in.
+
+You could make the SPI layer stuff look like a normal JDBC driver to
+user code--PL/Perl does this kind of thing with the Perl DBI
+interface.
+
+-Doug
+--
+Let us cross over the river, and rest under the shade of the trees.
+ --T. J. Jackson, 1863
+
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