This is a great discussion. I'm glad I started it! I like your
bottom line questions here Janet - I also look forward to
responses on these from those who know it better...
Regards,
Gregory
[EMAIL PROTECTED] wrote:
> Hi Brendan,
>
> Thanks VERY much!
>
> New ones:
> So with BEA WebLogic, if you are using the EJB capabilities, you really need to
> use Tuxedo with it for high performance database access? (or else plug in some
> other TM-like service?)
>
> How about in ND5.x.....if the app is using EJBs to do db stuff, is there any TM
> involved? Or does the ND5 EJB architecture still somehow manage to let the RDBMS
> handle it like ND4 does?
>
> Lastly, what are we really saying here?
> Do you think an EJB server + TM processes concurrent database requests as
> efficiently as the plain Corba-based "let-the-db-manage-all-the-db-action" (not
> sure the correct term?!) services that ND4 uses?
>
> Many thanks!
> Janet
>
>
> (Embedded
> image moved Brendan Johnston
> to file: <[EMAIL PROTECTED]>
> pic02195.pcx) 11/18/99 02:26 PM
>
>
> To: Janet Traub/IS/SSC/THD,
> [EMAIL PROTECTED]
> cc:
> Subject: RE: [ND] TP's and NetD
>
> Hi Janet,
>
> To answer your question,
>
> With any database or any EJB server, writes queue and happen one at a time.
>
> To go further,
>
> Writes happen one at a time with all databases.
> Writes happen one at a time with EJB.
>
> Any number of reads can happen simultaneously with all databases.
> One read happens at a time with EJB.
>
> With some databases reads can happen simultaneously with uncommitted writes
> and the older committed version of data is returned.
> With EJB reads do not happen simultaneously with writes.
>
> >From the point of view of concurrency, some databases are better than
> others, all EJB servers are worse than any major database.
> >From other points of view EJB servers have advantages.
>
> Brendan
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, November 18, 1999 10:10 AM
> To:
> [EMAIL PROTECTED]
> Subject: Re: [ND] TP's and NetD
>
> << File: pic06777.pcx >>
>
> Thanks Brendan. So is this statement:
>
> > Oracle will serialize 200 requests to update one row.
>
> explained by this passage:
>
> " This enables read only users of the database to view the
> old
> committed changes to the database while other uncommitted
> changes are made. This makes it possible for reads of a
> database to never block."
>
> or did you just mean it "queues" up the 200 requests to
> update the same row and
> processes them one by one?
>
> Thanks,
> Janet
>
> (Embedded
>
> image moved Brendan Johnston
>
> to file: <[EMAIL PROTECTED]>
>
> pic06777.pcx) 11/18/99 12:40 PM
>
> To: 'Aby Mathew' <[EMAIL PROTECTED]>
> cc:
> [EMAIL PROTECTED] (bcc: Janet
> Traub/IS/SSC/THD)
> Subject: Re: [ND] TP's and NetD
>
> Relational databases have locking and concurrency built in.
> If one user has an uncommitted change to a row, other
> attempts to update the
> row will block until the first user commits or rolls back.
>
> Unlike EJB servers, databases have separate read and write
> locks, deadlock
> detection and resolution. There are tools in most
> relational databases to
> kill particular processes, to determine how many locks a
> process holds, how
> much IO and CPU a process is using, to automatically kill
> processes which
> use more than some limit of locks, CPU, IO etc for the user
> or session.
>
> Some databases (Yes - Oracle, PostgreSQL, Solid, Interbase.
> Not - DB2,
> MSSQL, Sybase) have versioning. This enables read only
> users of the
> database to view the old committed changes to the database
> while other
> uncommitted changes are made. This makes it possible for
> reads of a
> database to never block.
>
> EJB's are typically non reentrant. This reduces
> concurrency.
>
> Brendan
>
> -----Original Message-----
> From: Aby Mathew
> [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, November 17, 1999 5:43 PM
> To: 'Brendan Johnston'
> Cc:
> [EMAIL PROTECTED]
> Subject: RE: [ND] TP's and NetD
>
> Brendan,
>
> Could you elaborate a little on this:
> > Oracle will serialize 200 requests to update one
> row.
>
> Thanks,
> Aby
>
> > -----Original Message-----
> > From: Brendan Johnston
> [mailto:[EMAIL PROTECTED]]
> > Sent: Wednesday, November 17, 1999 2:44 PM
> > To: Gregory Bohmer
> > Cc:
> [EMAIL PROTECTED]
> > Subject: Re: [ND] TP's and NetD
> >
> >
> > Gregory,
> >
> > Standard WebLogic does not come with Tuxedo.
> > Oracle will serialize 200 requests to update one
> row.
> >
> > Brendan
> >
> >
> > -----Original Message-----
> > From: Curt Springer
> > [mailto:[EMAIL PROTECTED]]
> > Sent: Wednesday, November 17, 1999
> 11:56
> AM
> > To: Gregory Bohmer
> > Cc:
> >
> [EMAIL PROTECTED]
> > Subject: Re: [ND] TP's and NetD
> >
> > Standard ND (not using PACs, EJBs, just
> using RDBMS/JDBC
> > service) has no
> > concept of data integrity, AFAIK. It
> only
> manages
> > resources, i.e., how
> > many requests are outstanding, and how
> many
> db
> > connections
> > are available at
> > the moment. What those requests are
> doing
> is somebody
> > else's department.
> >
> > - Curt Springer, Team ND
> >
> >
> > At 02:39 PM 11/17/99 -0500, Gregory
> Bohmer
> wrote:
> > >Here's a general question for
> everybody. I
> recognize
> > >that BEA WebLogic uses their own TP
> Monitor
> called
> > >Tuxedo to help queue update/delete
> requests, and ensure
> > >data integrity. What does NetD use?
> For
> instance,
> > >if 200 threads on the server (from
> client
> > calls) are all
> > trying
> > >to simulataneously update the same row
> in
> the
> > underlying
> > >Oracle database, what kind of queuing
> and
> the like are
> > >occuring in the NetD app server?
> > >
> > >How does this translate to the
> PeopleSoft
> PAC?
> > >
> > >Thanks as always.
> > >
> > >Regards,
> > >Gregory, HHMI
> > >
> >
> >
>
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>
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