What is really great about IAS 4.0 is that it supports custering and
failover of all three types of beans
1. Stateful Session Beans (Many products do not support this)
2. Stateless Session Beans
3. Entity Beans
if you go to the following link you will find a great paper on clustering:
http://www.borland.com/appserver/papers/
Extract
============================================================================
==============
IAS 4 supports heterogeneous clustering where any number of beans can be
clustered across any
number of Application Servers. Heterogeneous clustering imposes no
restrictions on the types of
beans or drivers that can appear on the various Application Servers within
the cluster.
This is in stark contrast to the clustering approach of most other
application servers, which allow
only homogeneous cluster ing : they impose restrictions on the way that
beans can be clustered
across servers. In these products, each Application Server in the cluster
must contain the exact bean
and JDBC driver configuration that every other Application Server in the
cluster contains. In fact,
each server must have the exact same EJB services running and they must even
be started in the
exact same order in order to create a cluster. In real world situations, is
very reasonable to expect an
application server in a cluster located in London to write data to a
database in London, and another
server in a cluster in New York to write to data in a database in New York.
This scenario is just
not possible using clustering features of many application servers. Some
products have the further
restriction that unless the server in New York and London are located on the
same LAN and can be
accessed via an IP multi-cast they cannot be clustered at all.
With Inprise Application Server, Inprise leverages the years of experience
in building scalable
middleware such as the award-winning VisiBroker (the most deployed CORBA
product), which
included robust implementations of load balancing, high availability and
failover. With Inprise
Application Server, these features have been taken to the "next level" with
stronger integration with
enterprise naming service and special attention to the clustering of
servlets, JSP, and EJBs.
The Inprise Application Server delivers scalability and high availability
for your E-commerce
applications, without limits.
============================================================================
==================
Now with some other clustering implementations, what you really get is a
house of cards.
William Louth
> -----Original Message-----
> From: Eyal Hirsch [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, February 29, 2000 9:00 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Clustering with automatic failover of entity beans?
> (Provided by any vendors?)
>
> Hi Dan,
> <vendor>
> Take a look at the following address for how Inprise in
> Inprise Application Server 4 implements what you need :
> http://www.borland.com/devsupport/appserver/faq/Availability_Scalability_P
> erformance.html
>
> This is from the document there :
>
> Failover is supported by leveraging the Naming Service and the osagent. We
> support failover of all types of EJBs. To summarize the behavior:
>
> 2) Entity Beans. From the Container standpoint, Entity Beans are similar
> to Stateless Session Beans, except that before being able to use a replica
> entity, it needs to be loaded in. The current transaction will fail, as it
> should. Both the resource and the synchronization objects associated with
> the original (failed) entity in VM 1 will be unavailable, and the
> transaction manager, presuming rollback (as per the OTS/JTS specification)
> will roll back the current transaction. However, subsequent transactions
> will simply fail-over to use the replica entity in VM 2, and will continue
> correctly.
>
>
>
>
> </vendor>
>
> eyal.
>
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