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Date: Wed, 05 Dec 2001 20:39:28 +0100

From: Laszlo Hornyak <hornyakl@freemail.hu>

Reply-To: hornyakl@users.sourceforge.net

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To: Barry Lind <barry@xythos.com>, pgsql-hackers@postgresql.org,

pgsql-jdbc@postgresql.org

Subject: Re: [HACKERS] [GENERAL] java stored procedures

References: <3C074DE4.9040905@freemail.hu> <3C0BE325.3020809@xythos.com> <3C0C937E.9000405@freemail.hu> <3C0CFD82.1030600@xythos.com> <3C0D219C.1090804@freemail.hu> <3C0D799D.4010808@xythos.com> <3C0DE382.1050400@freemail.hu> <3C0E5A23.7060701@xythos.com>

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Barry Lind wrote:

>

> I also stopped cc'ing the general list, since this is getting too

> detailed for most of the members on that list.

Ok.

> Now to your mail:

>

> This seems like a reasonable approach and should work across different

> JVMs. It would probably be a good experiment to try this with the Sun

> or IBM jvm at some point to verify. What I was afraid of was that you

> were hacking the Kaffe code to perform the integration which would

> limit this solution to only using Kaffe.

I am sure they wont work the same way. I think I have a sun jdk 1.3.0-2,

so I will try to port it soon. The IBM implementation must wait I think

until january.

>

> Just a suggestion: PL/J might be a good name, since as you probably

> know it can't be called pl/java because of the trademark restrictions

> on the word 'java'.

Ok, you won, I do not read the licenses. From now it`s name is pl/j.

Isn`t 'j' too short for the name of the process that runns java? :)

>

> I am a little concerned about the stability and complexity of having

> this '-pizza' program be responsible for handling the calls on the

> java side. My concern is that this will need to be a multithreaded

> program since multiple backends will concurrently be needing to

> interact with multiple java threads through this one program. It

> might be simpler if each postgres process directly communicated to a

> java thread via a tcpip socket. Then the "-pizza" program would only

> need to be responsible for starting up the jvm and creating java

> threads and sockets for a postgres process (it would perform a similar

> role to postmaster for postgres client connections).

With good design we can solve stability problems. As much as I know, if

postmaster dies, the postgres server becomes unavailable, this looks the

same problem. I do not know if we realy need sockets. Anyway, if 'j'

dies, we can create a new one, and restart calculations. Some watchdog

functionality...

Doing thing with sockets need a lot of rework. It is the best time for

this, while there is not too much thing done.

>>>

>>>> -when java thread receives the signal, it reads the message(s) from

>>>> the queue, and starts some actions. When done it tells postgres

>>>> with a signal that it is ready, and it can come for its results.

>>>> This will be rewritten see below problems.

>>>

>>> Are signals the best way to accomplish this?

>>

>> I don`t know if it is the best, it is the only way I know :)

>> Do you know any other ways?

>>

> I don't know, but hopefully someone on the hackers list will chip in

> here with a comment.

After a first developement cycle (if my brain doesn`t burn down), the

signals can be replaced to a plugable communication interface I think.

So maybe we can use CORBA, or sockets, or something else. This will take

a lot of time.

> OK, so the same backend process that called the function gets messaged

> to process the sql. This should work. However it means you will need

> a special version of the jdbc driver that uses this shm+signals

> communication mechanism instead of what the current jdbc driver does.

> This is something I would be happy to help you with.

This is kind of you. :)

For this, I will have to finish the protocol of communication. I have to

learn Postgres enough, so I am not sure this will be done this weekend.

I have ideas, only time is needed to implement them or to recognize the

failures.

Thanks,

Laszlo Hornyak

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From pgsql-hackers-owner+M16313=candle.pha.pa.us=pgman@postgresql.org Thu Dec 6 10:01:29 2001

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Date: Thu, 06 Dec 2001 15:23:39 +0100

From: Laszlo Hornyak <hornyakl@freemail.hu>

Reply-To: hornyakl@users.sourceforge.net

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To: Gunnar =?ISO-8859-1?Q?R=F8nning?= <gunnar@polygnosis.com>

cc: Barry Lind <barry@xythos.com>, pgsql-hackers@postgresql.org,

pgsql-jdbc@postgresql.org

Subject: Re: [HACKERS] [GENERAL] java stored procedures

References: <3C074DE4.9040905@freemail.hu> <3C0BE325.3020809@xythos.com><3C0C937E.9000405@freemail.hu> <3C0CFD82.1030600@xythos.com> <m2zo4wttp1.fsf@smaug.polygnosis.com>

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Hi!

Sorry, I have time only for short ansvers, it is company time :((.

Gunnar R�nning wrote:

>* Barry Lind <barry@xythos.com> wrote:

>|

>| possible problems with your strategy). Without knowing what exactly

>| you are thinking of doing it is difficult to comment.

>

>Agreed.

>

Ok, I will try to bring the code here before Monday, or at least some

pieces. It is full of hardcoded constants from my developement

environment. :(

>

>| I am very interested in hearing what your plans are for pl/java. I

>| think this is a very difficult project, but one that would be very

>| useful and welcome.

>

>I would very much like to hear about the plans myself.

>

I do not see so big difficulities yet, am I so lame? It won`t be easy,

realy, we should keep it simple, at least becouse of me.

thanks,

Laszlo Hornyak

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From pgsql-hackers-owner+M16334=candle.pha.pa.us=pgman@postgresql.org Thu Dec 6 16:11:23 2001

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Date: Thu, 06 Dec 2001 23:02:51 +0500

From: Hannu Krosing <hannu@tm.ee>

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To: hornyakl@users.sourceforge.net

cc: Gunnar =?ISO-8859-1?Q?R=F8nning?= <gunnar@polygnosis.com>,

Barry Lind

<barry@xythos.com>, pgsql-hackers@postgresql.org,

pgsql-jdbc@postgresql.org

Subject: Re: [HACKERS] [GENERAL] java stored procedures

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Laszlo Hornyak wrote:

>>

>> | I am very interested in hearing what your plans are for pl/java. I

>> | think this is a very difficult project, but one that would be very

>> | useful and welcome.

>>

>> I would very much like to hear about the plans myself.

>

> I do not see so big difficulities yet, am I so lame? It won`t be easy,

> realy, we should keep it simple, at least becouse of me.

Let me propose a very different approach to PL/J - use gcc-java and

figure out the problems

with (dynamic) compiling and dynamic linking.

This is an approach somewhat similar to .NET/C# that you first compile

things and then run instead

of trying to do both at the same time ;)

Oracle /may/ be doing something similar with their java stored

procedures, as they claim these to be "compiled".

-----------------

Hannu

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