Re: connection pooling from an application server to oracle

From: David Hau <davehau123_at_netscape.net>
Date: Mon, 15 Dec 2003 16:54:34 -0800
Message-ID: <F001.005D9FAA.20031215165434@fatcity.com>

 From 9i on, application servers can actually make use of the connection pooling and session pooling features within OCI instead of implementing their own.

An interesting concept is how the 9i OCI API separates the notion of session pooling from connection pooling. You can have multiple session pools and multiple connection pools at the same time in an environment.   A session pool is a pool of user handles. A connection pool is a pool of server handles. A session pool on top of a single physical connection means you can multiplex multiple sessions on a single connection by switching in and out of different transaction contexts.   What's neater is having a session pool on top of a connection pool. You can multiplex say 10 sessions on top of 5 physical connections. Each time you obtain a session, you specify which session pool and which connection pool you want to use.

Also, I believe that the client can store a pointer to a transaction context on the server side. This means you don't need to tie a physical connection to a transaction. You can use a different physical connection for each step of a transaction simply by passing it the pointer to the transaction context corresponding to that transaction.

I think the JDBC driver has connection pooling also, but not session pooling. OCCI might have both. But I haven't checked.

BTW, connection pooling and session pooling are new features in the 9i OCI. The 8i OCI does not have these features.

Regards,
Dave

vadim.gorbounov_at_sigma-systems.com wrote:

> Mladen,
> Probably, something is very wrong with application design.
>
>

>>With iPlanet, it looks like this: 
>>Application invokes bean, pumpkin or servlet which has something to do 
>>with oracle. The app server pooling mechanism will allocate one of the
>>already established dedicated server connections, which will perform the
>>work. When the same user executes another vegetable (EJB or servlet), he
>>or she may do so within a different dedicated server connection. We have a 
>>situation in which a single user utilizes several dedicated server

>
> connections
>

>>within a single logical screen. 

>
>
> Usually application server is smart enough (we use Weblogic) to reuse same
> physical connection if any number of calls comes from any different places
> once all the calls are a single transaction.
> I can imagin single call to allocate more than one connection if more than
> one transaction contexts required for this call (although, smartest app
> servers and the best databases can optimize even this transaction can be
> suspended and then resumed after another transaction commits), but it must
> be some very special need - it is not common what I'm saying.
> Single logical screen probably cannot use connections at all: screen means
> control is on users side means transaction should not be opened means no
> connection assigned .
> So, it's probably not an architecture's fault, it's design issue.
>
> Regards
>
> Vadim

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Author: David Hau
  INET: davehau123_at_netscape.net

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Received on Mon Dec 15 2003 - 18:54:34 CST