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Jaguar Question

7 posts in General Discussion (old) Last posting was on 2000-03-03 00:29:26.0Z
Eyal Mishor Posted on 2000-03-01 21:49:34.0Z
Newsgroups: sybase.public.easerver
Date: Wed, 01 Mar 2000 23:49:34 +0200
From: Eyal Mishor <eyal_mi@zahav.net.il>
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Hi,

What will happen if two clients address the same entity bean ?
Will Jaguar create one instance of that bean that will serve both
clients or create two instances, one per client ?

Eyal Mishor


Dave Wolf [Sybase] Posted on 2000-03-02 13:29:12.0Z
Newsgroups: sybase.public.easerver
From: "Dave Wolf [Sybase]" <dwolf@sybase.com>
Subject: Re: Jaguar Question
Date: Thu, 2 Mar 2000 08:29:12 -0500
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Two instances of the bean and the data is synchronized at the database.

Dave Wolf
Internet Applications Division

"Eyal Mishor" <eyal_mi@zahav.net.il> wrote in message
news:38BD906E.17BDC37E@zahav.net.il...
> Hi,
>
> What will happen if two clients address the same entity bean ?
> Will Jaguar create one instance of that bean that will serve both
> clients or create two instances, one per client ?
>
> Eyal Mishor
>


Scott McReynolds [Sybase] Posted on 2000-03-02 06:19:55.0Z
Newsgroups: sybase.public.easerver
From: "Scott McReynolds [Sybase]" <scottmc@sybase.com>
Subject: Re: Jaguar Question
Date: Wed, 1 Mar 2000 23:19:55 -0700
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Eyal,

If they try to access the bean at the same time we will create 2 copies of
the bean. that is what the spec requires us to do.

Scott

Eyal Mishor <eyal_mi@zahav.net.il> wrote in message
news:38BD906E.17BDC37E@zahav.net.il...
> Hi,
>
> What will happen if two clients address the same entity bean ?
> Will Jaguar create one instance of that bean that will serve both
> clients or create two instances, one per client ?
>
> Eyal Mishor
>


Eyal Mishor Posted on 2000-03-02 22:22:36.0Z
Newsgroups: sybase.public.easerver
Date: Fri, 03 Mar 2000 00:22:36 +0200
From: Eyal Mishor <eyal_mi@zahav.net.il>
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Article PK: 154518

As far as I understand the spec it lets you keep only one instance which has
an exclusive access
to the persistent storage, so in the next transaction there is no need to
ejbLoad.

I'll try to rephrase my question to be more specific:
I have a bean managed entity bean, and I want to reduce the database access of
ejbLoad.
Can I check at the beginning of ejbLoad if the bean is already loaded (by
examining for a none null id field,
for example) and not refresh the bean from the database in that case ? This
will be legal if I always get
the same instance of the bean.

"Scott McReynolds [Sybase]" wrote:

> Eyal,
>
> If they try to access the bean at the same time we will create 2 copies of
> the bean. that is what the spec requires us to do.
>
> Scott
>
> Eyal Mishor <eyal_mi@zahav.net.il> wrote in message
> news:38BD906E.17BDC37E@zahav.net.il...
> > Hi,
> >
> > What will happen if two clients address the same entity bean ?
> > Will Jaguar create one instance of that bean that will serve both
> > clients or create two instances, one per client ?
> >
> > Eyal Mishor
> >


Scott McReynolds [Sybase] Posted on 2000-03-03 00:07:48.0Z
Newsgroups: sybase.public.easerver
From: "Scott McReynolds [Sybase]" <scottmc@sybase.com>
Subject: Re: Jaguar Question
Date: Thu, 2 Mar 2000 17:07:48 -0700
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Eval,

You can, but be very careful with this. The problem is that if you have 2
copies of the same entity bean in memory then the database may change
between calls from the client and the changes would not be reflected in the
bean. If you are wanted to get multiple fields back from the bean use a
serializable object to pass multiple fields to and from the bean.

Scott

Eyal Mishor <eyal_mi@zahav.net.il> wrote in message
news:38BEE9AC.4B3416B0@zahav.net.il...
> As far as I understand the spec it lets you keep only one instance which
has
> an exclusive access
> to the persistent storage, so in the next transaction there is no need to
> ejbLoad.
>
> I'll try to rephrase my question to be more specific:
> I have a bean managed entity bean, and I want to reduce the database
access of
> ejbLoad.
> Can I check at the beginning of ejbLoad if the bean is already loaded (by
> examining for a none null id field,
> for example) and not refresh the bean from the database in that case ?
This
> will be legal if I always get
> the same instance of the bean.
>
>
> "Scott McReynolds [Sybase]" wrote:
>
> > Eyal,
> >
> > If they try to access the bean at the same time we will create 2 copies
of
> > the bean. that is what the spec requires us to do.
> >
> > Scott
> >
> > Eyal Mishor <eyal_mi@zahav.net.il> wrote in message
> > news:38BD906E.17BDC37E@zahav.net.il...
> > > Hi,
> > >
> > > What will happen if two clients address the same entity bean ?
> > > Will Jaguar create one instance of that bean that will serve both
> > > clients or create two instances, one per client ?
> > >
> > > Eyal Mishor
> > >
>


Dave Wolf [Sybase] Posted on 2000-03-03 00:25:15.0Z
Newsgroups: sybase.public.easerver
From: "Dave Wolf [Sybase]" <dwolf@sybase.com>
Subject: Re: Jaguar Question
Date: Thu, 2 Mar 2000 19:25:15 -0500
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Eyal,

Please see section 9 of the EJB 1.1 spec. It does not require that each row
have just one instance of an EntityBean. If you see the first figure we can
make multiple beans to represent each row and use the database to synchonize
the access to the data.

Dave Wolf
Internet Applicaitons Division

"Scott McReynolds [Sybase]" <scottmc@sybase.com> wrote in message
news:iLOp8TKh$GA.295@forums.sybase.com...
> Eval,
>
> You can, but be very careful with this. The problem is that if you have 2
> copies of the same entity bean in memory then the database may change
> between calls from the client and the changes would not be reflected in
the
> bean. If you are wanted to get multiple fields back from the bean use a
> serializable object to pass multiple fields to and from the bean.
>
> Scott
>
> Eyal Mishor <eyal_mi@zahav.net.il> wrote in message
> news:38BEE9AC.4B3416B0@zahav.net.il...
> > As far as I understand the spec it lets you keep only one instance which
> has
> > an exclusive access
> > to the persistent storage, so in the next transaction there is no need
to
> > ejbLoad.
> >
> > I'll try to rephrase my question to be more specific:
> > I have a bean managed entity bean, and I want to reduce the database
> access of
> > ejbLoad.
> > Can I check at the beginning of ejbLoad if the bean is already loaded
(by
> > examining for a none null id field,
> > for example) and not refresh the bean from the database in that case ?
> This
> > will be legal if I always get
> > the same instance of the bean.
> >
> >
> > "Scott McReynolds [Sybase]" wrote:
> >
> > > Eyal,
> > >
> > > If they try to access the bean at the same time we will create 2
copies
> of
> > > the bean. that is what the spec requires us to do.
> > >
> > > Scott
> > >
> > > Eyal Mishor <eyal_mi@zahav.net.il> wrote in message
> > > news:38BD906E.17BDC37E@zahav.net.il...
> > > > Hi,
> > > >
> > > > What will happen if two clients address the same entity bean ?
> > > > Will Jaguar create one instance of that bean that will serve both
> > > > clients or create two instances, one per client ?
> > > >
> > > > Eyal Mishor
> > > >
> >
>
>


Dave Wolf [Sybase] Posted on 2000-03-03 00:29:26.0Z
Newsgroups: sybase.public.easerver
From: "Dave Wolf [Sybase]" <dwolf@sybase.com>
Subject: Re: Jaguar Question
Date: Thu, 2 Mar 2000 19:29:26 -0500
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You can mark entity bean methods as read only so we dont call ejbStore()
each time.

EntityBeans are just chatter boxes with the database. Nature of the beast.

Dave Wolf
Internet Applications Division

"Eyal Mishor" <eyal_mi@zahav.net.il> wrote in message
news:38BEE9AC.4B3416B0@zahav.net.il...
> As far as I understand the spec it lets you keep only one instance which
has
> an exclusive access
> to the persistent storage, so in the next transaction there is no need to
> ejbLoad.
>
> I'll try to rephrase my question to be more specific:
> I have a bean managed entity bean, and I want to reduce the database
access of
> ejbLoad.
> Can I check at the beginning of ejbLoad if the bean is already loaded (by
> examining for a none null id field,
> for example) and not refresh the bean from the database in that case ?
This
> will be legal if I always get
> the same instance of the bean.
>
>
> "Scott McReynolds [Sybase]" wrote:
>
> > Eyal,
> >
> > If they try to access the bean at the same time we will create 2 copies
of
> > the bean. that is what the spec requires us to do.
> >
> > Scott
> >
> > Eyal Mishor <eyal_mi@zahav.net.il> wrote in message
> > news:38BD906E.17BDC37E@zahav.net.il...
> > > Hi,
> > >
> > > What will happen if two clients address the same entity bean ?
> > > Will Jaguar create one instance of that bean that will serve both
> > > clients or create two instances, one per client ?
> > >
> > > Eyal Mishor
> > >
>