1. A TP is essential if you want to manage transactions which span more
than one database
2. A TP also enables components to be written without managing
transactions themselves which allows them to be wired together in a variety
of ways
3. A TP has security features (who is this client, can this method be
called by this client)
4. A TP manages server resources i.e. it can pool database connections
etc.
A fully compliant EJB server provides this stuff too. ND does 2, 3 and 4
for EJBs although I don't think it does 1.
A transaction which spans multiple databases requires a 2 phase commit,
which is less efficient than a transaction contained within one database.
The transactions which last the entire length of an EJB method call may be
larger than is necessary reducing concurrency from the optimal.
If you use CORBA with a transaction service, security service etc. you
essential have EJB.
Tuxedo would have a lot of management and monitoring tools. It would
probably have means to tune and configure it etc.
If your environment involves one database and one application server you
don't need a TP monitor. A TP monitor is useful for large complex sites.
Brendan
-----Original Message-----
From: Gregory Bohmer [mailto:[EMAIL PROTECTED]]
Sent: Thursday, November 18, 1999 12:22 PM
To: [EMAIL PROTECTED]
Cc:
[EMAIL PROTECTED]
Subject: Re: [ND] TP's and NetD
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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> Encoding: base64
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