SO Load Balancing Question

Question

Hi all,
I have a service object (SO1) which has been set to Load Balancing.
This service object has an attribute which serves as a number allocator
(NA1).
This NA1 provides a unique number across the whole application for each of
the record that require to store into DB.
The problem is, will the NA1 get replicated if the SO1 is replicated?
If yes, will NA1 crash?
Regards,
Martin Chan
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Senior Analyst/Programmer
Dept of Education and Training
Mobile : [phone]
Email: martin.chandet.nsw.edu.au
Tel: [phone]

Answer 1

Hi Serge,
Could you prefix it with the PID of the load balanced process ?No I can't. At least not at the moment.
When a service object is replicated, it is automatically replicated into adifferent partition...
Thanks.
An advice, make the NA1 shared. So if you get to do multithreaded accessto
it, you won't screw up things.I am thinking it may be better off to create it as a service object on it's
own.
How is the number returned by the NA1 generated ?It gets generated by Forte's code.
... Try to make it so that the
load balanced partitions don't need to access the database more than onein
5 min. to get a new Seed Key. This would not need to PID.Thanks for your advise.
Regards
Martin Chan
-----Original Message-----
From: Serge Blais [mailto:Serge.BlaisSun.com]
Sent: Tuesday, 3 April 2001 14:17
To: Chan, Martin
Subject: RE: (forte-users) SO Load Balancing Question
Your right, they can generate the same number. How much control do you have
over the ID being generated? Could you prefix it with the PID of the load
balanced process ?
Just a note: When a service object is replicated, it is automatically
replicated into a different partition, possibly on the same machine or on a
different one.
An advice, make the NA1 shared. So if you get to do multithreaded access to
it, you won't screw up things.
How is the number returned by the NA1 generated ? If NA1 is using a stored
procedure, or something like:
Start TRX
read number
newnumber = number+5000
write back newnumber
End Trx
Something like will be very safe. The Database Index Table is taking care
of the critical section. Then you can be sure that each replicate can be
independent (not hit into each other) for 5000 iterations. Depending on the
frequency, you may want to up this number or lower this number. Too high it
would make the key very high very soon with wholes in the sequence. Too low
and you would have hit between the replicates. Try to make it so that the
load balanced partitions don't need to access the database more than one in
5 min. to get a new Seed Key. This would not need to PID.
Serge
At 01:59 PM 4/3/2001 +1000, you wrote:
Hi Serge,
The number return by the NA1 is used as a primary key for each of therecord
that stores in the DB.
The Number Allocator NA1 is required to access to DB to update an ID table
which carry the next available sequence number. NA1 will only update this
table for every 5000 records.
For example, the initial value of the sequence is: 1
The next update will change the value to 5001, next will be 10001 and soon.
>
The properties of this NA1 class at runtime
Shared - Disallowed
Distributed - Disallowed
Transactional - Is Default
Monitored - Disallowed
Unfortunately, this attribute is not a handle but is instantiated by theSO1
itself.
I have been thinking, if SO1 is replicated within the same partition, and
each replicate will carry its own NA1. NA1 and the replicate of NA1 may
return a same number if their initial values of the sequence are the same.
Correct?
Regards
Martin Chan
-----Original Message-----
From: Serge Blais [mailto:Serge.BlaisSun.com]
Sent: Tuesday, 3 April 2001 13:11
To: Chan, Martin; forte-userslists.xpedior.com
Subject: Re: (forte-users) SO Load Balancing Question
Let's see if I understand right.
You have a service object that keep a handle to an object that either keep
state information, or that generate state information. Now the thing to
figure out is which is it. Let's assume that NA1 is a number generator,
that does not need to be synchronized or that doesn't need to access any
external resource. It would still work, depending on the algorythm you are
using.
Will they share the same NA1? It depends on the nature of NA1, but for sure
NA1 would have to be an anchored object. An if multiple partitions would
share the same object "only" for key generation, you would bring down your
performance on key generation or key update (by adding one inter-process
call).
In short:
1. Many scenarios can happen, you need to be clearer on your description.
2. If you are sharing an object by load balanced partitions, this greatly
reduce the gain of load balancing the partition.
3. If NA1 is keeping state, any access to it would need to be controlled
"shared".
Have fun now...
Serge
At 12:30 PM 4/3/2001 +1000, Chan, Martin wrote:
Hi all,
I have a service object (SO1) which has been set to Load Balancing.
This service object has an attribute which serves as a number allocator
(NA1).
This NA1 provides a unique number across the whole application for each
of
the record that require to store into DB.
The problem is, will the NA1 get replicated if the SO1 is replicated?
If yes, will NA1 crash?
Regards,
Martin Chan
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Senior Analyst/Programmer
Dept of Education and Training
Mobile : [phone]
Email: martin.chandet.nsw.edu.au
Tel: [phone]
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Serge.BlaisSun.comSerge Blais
Professional Services Engineer
iPlanet Expertise Center
Sun Professional Services
Cell : [phone]
Serge.BlaisSun.com