Question on clusters

I made a simple VI which uses a cluster (Name and Age). Now from my main VI,
I pass a cluster to this subVI and everything works OK.
In this example, I placed a cluster on the front panel. Now what I am trying
to do is NOT use a cluster on front panel, only have Name and Age controls
on the front panel but still able to pass a cluster from my main VI to the
subVI. Not sure if I explained myself clearly or not. Basically I am looking
for a way to define my Cluster and after doing that, be able to pass cluster
from main VI to subVI without using cluster control on the front panel
(don't care about GUI).
vishi
[Attachment TestCluster.vi, see below]
Attachments:
TestCluster.vi ‏12 KB

There are two ways of doing what you want. You can have seperate inputs on the Front Panel and then use a "bundler" to combine them; OR you can use a cluster that you have turned the frame of transparent.
The attached VI shows both. Note that despite their structural differences, they are indistinguishable from the front panel.
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps
Attachments:
clusters.vi ‏12 KB

Similar Messages

Questions on clustering

Hi,
          I am on weblogic 7.0 sp2, jdk1.3.1 and solaris 8. I have a couple of
          questions regarding clustering in production.
          1. Is it a good thing to run the admin server on a small linux box and
          weblogic
          clustered servers on big solaris boxes?
          2. Is it good to have the clustered URL as
          t3://server-1:port-1,server-2:port-2....server-n:port-n or to have it as
          t3://cluster:port
          and all the entries in the DNS server?


That's because DNS round robin should allow better failover for
          initialcontext calls via container / clients in certain scenarios. I am not
          too familiar with it but will try to find out some additional detail for
          you.
          sree
          "Shiva P" <[email protected]> wrote in message
          news:[email protected]...
          > Thanks. For the 2nd question can you also tell me the reasons? I am just
          curious
          > out
          > here and nothing more than that.
          >
          > Shiva.
          >
          > Sree Bodapati wrote:
          >
          > > Hi Shiva,
          > >
          > > Please see my answers inline,
          > >
          > > "Shiva P" <[email protected]> wrote in message
          > > news:[email protected]...
          > > > Hi,
          > > > I am on weblogic 7.0 sp2, jdk1.3.1 and solaris 8. I have a couple of
          > > > questions regarding clustering in production.
          > > >
          > > > 1. Is it a good thing to run the admin server on a small linux box and
          > > > weblogic
          > > > clustered servers on big solaris boxes?
          > >
          > > It should be fine. I dont think that would be anything different except
          that
          > > you need to make sure to test it out and ensure the linux kernel
          properties
          > > are properly tuned (not sure which will be applicable to your env)
          > > especially when doing deployment of application. Check it out and post a
          > > note here if you find something different that you need help with.
          > >
          > > > 2. Is it good to have the clustered URL as
          > > > t3://server-1:port-1,server-2:port-2....server-n:port-n or to have it
          as
          > > > t3://cluster:port
          > > > and all the entries in the DNS server?
          > > >
          > >
          > > t3://cluster:port is prefered in production environments (the url should
          be
          > > the DNS entry pointing to all ips of the machines in the cluster).
          > >
          > > /
          > > sree
          >

Several questions on Clustering

Hi,
          I have some very basic questions on clustering within WebLogic :
          1. We need to use startup classes to solve several different problems within
          our environment. But, we want to make sure that these services can use
          WebLogic's load-balancing and failover mechanisms. Are startup classes
          clusterable ? If I register a startup class in the cluster-wide properties
          file, does every WebLogic server running within the cluster get an instance
          of the startup class ?
          2. Are stateless RMI objects clusterable ?
          Thanks.
          Ashok


          Ashok Nare wrote:
          > Hi,
          >
          > I have some very basic questions on clustering within WebLogic :
          >
          > 1. We need to use startup classes to solve several different problems within
          > our environment. But, we want to make sure that these services can use
          > WebLogic's load-balancing and failover mechanisms. Are startup classes
          > clusterable ?
          Only RMI classes can use load-balancing and failover mechanisms.
          > If I register a startup class in the cluster-wide properties file, does every
          > WebLogic server running within the cluster get an instance of the startup
          > class ?
          It depends on what kind of class it is, and how your environment is setup.
          > 2. Are stateless RMI objects clusterable ?
          Yes
          > Thanks.
          > Ashok

Question on clustering and J2EE Environment Entries

Does anyone know if changes made through the admin server console to J2EE
          environment entries are propagated to the managed servers without
          redeploying the entire app. I can find a reference similar to this for
          things in the config.xml which states they are propagated in memory (in most
          cases) and can optionally be written permanently to the confg.xml file. I
          can't find a reference that tells me how/what is done for J2EE environment
          values.
          If this is not possible, how does one do dynamic configuration setting for a
          J2EE application in a clustered environment?
          Kent


What I'm talking about is the environment entries that are set in the web
          application deployment descriptor (web.xml) from the admin server console.
          You go to a specific web-app in the console and then click on "edit web
          application deployment descriptor". From there (towards the bottom of the
          tree on the left) is Env Entry. You can change Environment Entries in the
          DD. What is unclear is if the values are propagated to the running app
          (in memory). For example, if I have a servlet that reads this environment
          entry and I change it in the admin console is the new value reflected
          (relatively) immediately? It's not entirely clear.
          Since there is an option to "persist" these changes (in the top of the tree)
          that would seem to imply that the changes are propagated to the running
          instances in memory otherwise why would I not want to persist the change?
          On the other hand, I would have also expected a button to let me decide when
          to push the changes so I could control when the managed server know about
          the change (for example, if I had to set more than one property to configure
          something).
          So ... does this make my question clearer? And if so is there any
          documentation the describes this? If not how do people handle configuration
          of a running application in a cluster if it not through DD environment
          entries?
          Kent
          "Cameron Purdy" <[email protected]> wrote in message
          news:[email protected]...
          > > Actually I'm talking about what I would call "environment variables" if
          > this
          > > was unix. I am not talking about files (gifs, html, etc) but rather
          > porpety
          > > settings. It is my understanding that these are call "environment
          > entries"
          > > (but I may remembered the name wrong) and are typed values that can be
          > > looked up vi JNDI.
          >
          > You can programmatically set JNDI entries, and they will usually be
          > propagated (although they are not designed to be reliably replicated).
          > Furthermore, the death of the registering server will cause the death of
          the
          > JNDI entries.
          >
          > I don't know how to set them from the console.
          >
          > Peace,
          >
          > --
          > Cameron Purdy
          > Tangosol, Inc.
          > Clustering Weblogic? You're either using Coherence, or you should be!
          > Download a Tangosol Coherence eval today at http://www.tangosol.com/
          >
          >
          >
          > "Kent Mitchell" <[email protected]> wrote in message
          > news:[email protected]...
          > >
          >
          >
          >

Simple question on clustering

          Dear all,
          is there any way to detect the failure of any one WLS
          joining the same cluster? Or do we need to detect
          the failure by ourselves (e.g. tracing certain kind of log files)?
          thanks!
          cheers,
          Ken


I'd guess not, since we've been told there's no way in weblogic to know when
          an existing server in a cluster fails. What you're asking sounds a little
          different, though, since you refer to failure when joining the cluster, so
          maybe there's a better answer.
          "Kenneth Yue" <[email protected]> wrote in message
          news:3ab9b85c$[email protected]..
          Dear all,
          is there any way to detect the failure of any one WLS
          joining the same cluster? Or do we need to detect
          the failure by ourselves (e.g. tracing certain kind of log files)?
          thanks!
          cheers,
          Ken

IronPort Clustering questions

Hello all,
I have some questions about clustering in Ironport:
Actually I have one IronPort C150 in "Standalone mode" with an ip adress who takes the mail flow (192.168.1.34)
We received a second Ironport for setup a cluster configuration between them.
My question are :
1) What happen for the mail flow if the first IronPort ( 192.168.1.34) move to a cluster configuration ?
I have to configure a virtual address to be same of the original ip adress mail flow (192.168.1.34) or the cluster takes the original configuration of the first IronPort ?
2) If one Ironport Fail, the second IronPort automatically takes the mail? or i have to reconfigure manually the ip address ?
Thanks for your help.
PS: Sorry for my english

I agree with your thoughts on MX records. The biggest benefit to using a load balancer is with the management. Once you start getting a large number of hosts in an MX record you start running into problems with senders correctly resolving your MX records due to inproper DNS configuration on the internet (UDP vs TCP). Standing up a large number of hosts behind some load balancers is one potential solution. This of course comes with its own set of challenges.
I'm still using MX records, but at some point will need to look at having multiple machines behind each host in my MX records to cut down on the size of the returned record.
I just wish I could get all of my application developers to write their apps to understand MX records. Load balancers have worked well for my outbound environment where most applications are pointing at a host name instead of an MX record.
Joe

Question on Quorum

Hi Experts,
Couple of questions on Windows Clusters. I am not a cluster expert and look for some help to understand the concepts
1. In Win 2003 cluster, we have quorum disk and "Disk only quorum model". IF this quorum model is used, and if quorum disk is down, then cluster is down. So, my question is what quorum disk contain? All I know is, it contains cluster
related information. But what kind of info is stored in quorum disk which is so critical.
2. Secondly, from Win 2008 and above cluster, we have new quorum models(i.e node majority, node + disk witness ...), in these new quorum models, do we still have quorum disk? And where does cluster information is stored? I came to know that cluster information
is stored or replicated to all nodes and each node has its own copy. I wanted to know is this true or not. pl correct me if am wrong. If this information is correct, how does the cluster info replication happens? Can anybody explain in simple terms?
Any links/msdn blogs or resources would be a great help for reference.
Thanks in advance.

Hi Samantha v,
For 2003 cluster before giving an explanation of what a cluster quorum is, it is important to understand the background to Windows Clustering Technologies.
Starting with Microsoft® Windows NT® 4.0 Enterprise Edition, Microsoft introduced the idea of a cluster, which is simply a group of servers that are presented as one virtual
server. For example, you can configure two servers, server A and server B, in a cluster, and present them to the outside world as server C (a virtual server). If, for example, server A dies, server B is used to ensure that the virtual server (server C) and
the services it offered, are still available to clients, thereby providing transparent access to the user. You can refer the following related KB for more detail information:
Background (Server Clusters: Quorum Options - Windows Server 2003)
http://technet.microsoft.com/en-us/library/cc780689(v=ws.10).aspx
Quorum Drive Configuration Information
http://support.microsoft.com/kb/280345
Frequently Asked Questions (Server Clusters: Quorum Options - Windows Server 2003)
http://technet.microsoft.com/en-us/library/cc737067(v=ws.10).aspx
For 2008 or later cluster you can refer the following article:
New Cluster Quorum Models in Windows 2008
http://blogs.msdn.com/b/saponsqlserver/archive/2010/06/30/new-cluster-quorum-models-in-windows-2008.aspx
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Fault tolerant, highly available BOSE XI R2 questions

Post Author: waynemr
CA Forum: Deployment
I am designing a set of BOSE XI R2 deployment proposals for a customer, and I had a couple of questions about clustering. I understand that I can use traditional Windows clustering to setup an active/passive cluster for the input/output file repositories - so that if one server goes down, the other can seamlessly pick up where the other left off. On this Windows-based active/passive cluster, can I install other BOSE services and will they be redundant, or will they also be active/passive. For example: server A is active and has the input/output file repository services and the Page Server. Server B is passive and also has the input/output file repository services and the Page Server. Can the page Server on B be actively used as a redundant Page Server for the entire BOSE deployment? (probably not, but I am trying to check just to make sure) If I wanted to make the most fault-tolerant deployment possible, I think I would need to:Setup two hardware load-balanced web front-end serversSetup two servers for a clustered CMSSetup two web application servers (hardware load-balanced, or can BOSE do that load-balancing?)Setup two Windows-clustered servers for the input/output file repositoriesSetup two servers to provide pairs of all of the remaining BOSE services (job servers, page servers, webi, etc.)Setup the CMS, auditing, and report databases on a cluster of some form (MS SQL or Oracle)So 10 servers - 2 Windows 2003 enterprise and 8 Windows 2003 standard boxes, not including the database environment.Thanks!

Post Author: jsanzone
CA Forum: Deployment
Wayne,
I hate to beat the old drum, and no I don't work for BusinessObjects education services, but all of your questions and notions of a concept of operations in regards to redundancy/load balancing are easily answered by digesting the special BO course "SA310R2" (BusinessObjects Enterprise XI R1/R2 Administering Servers - Windows). This course fully covers the topics of master/slave operations, BO's own load balancing operations within its application, and pitfalls to avoid. Without attending this course, I for one would not have properly understood the BusinessObjects approach and would've been headed on a collision course with disaster in setting up a multi-server environment.
Best wishes-- John.

2003 Terminal Server Session Directory Clustering

Hi everybody ;
I have question about clustering TS Session Directory Service.
In my environment I have four terminal server which running Windows Server 2003 R2. Now we bought two new servers and we are planning to use them for File Server with Windows Server 2008 R2. I installed Windows Server 2008 R2 to this new servers
and i configured them for file server and clustered this two server. But i want to cluster the my terminal servers session directory service in this cluster environment. My terminal server WS2003 but cluster environment is WS2008. Is there a problem about
this version difference ?
Thanks.

i don't believe so. 2003 terminal services requires at least 2x 2003 servers with the session directory service running on them to be clustered in MSCS. 2008 has a whole new session directory which will not serve 2003 remote desktop hosts
http://support.microsoft.com/kb/301923
http://support.microsoft.com/kb/301926
http://download.microsoft.com/download/8/6/2/8624174c-8587-4a37-8722-00139613a5bc/TS_Session_Directory.doc
you may want to consider upgrading your old 2003 terminal server environment to 2008 though.

Some question on CORE BPEL ENGINE

Hello,
I've read Chapter 4 and now I've some question:
1-Clustering: What's you intend which expression "fail-over can be configured on the engine" and How? What Kind of clustering you realize (active-active, active-passive,...)?
2-I think that I don't exactly understand what you intend with "BPEL Compensating Transaction Model" could you give me more information about this?
thank you guys!
Andrea

1- I just completed a draft of a tech note on High Availability that I can share with you that explains the clustering model in detail. At a very high level, the BPEL Server is completely stateless and reliable, including a built-in recovery service that enables failover in case of failures. You don't need to cluster the app-server to be able to cluster BPEL servers (for either high availability or scalability).
2 - BPEL provides support for compensating transactions, which is an alternative transaction model when XA-style, ACID transactions can not be used (either due to the long-running nature of a "transaction" or the inclusion of services which don't support XA/JTA style transactions. We have code examples available for this and slides from our training course that discuss it.
Send me an email if you would like access to either of these documents. I'll also try to publish them to OTN in the next few days as tech notes, but in the meantime, I'm happy to share the information directly with any individuals who want it.
Dave
David Shaffer
Product Mgr, Oracle BPEL Process Manager
[email protected]
W: 650.506.1729
http://otn.oracle.com/bpel

BizTalk and SQL Clustering

Hi,
I have following questions in clustering:
1. When we say BizTalk cluster. Does that mean that all the server nodes that participate will use the same SQL server cluster, SSO cluster?
2. In case of SQL Server cluster, one is active and one is passive. Will both the servers be replica of each other? I mean to ask will they have same data and configuration? If not then how will it work in a failover scenario because the passive
instance will not the all the information of Active instance?
3. Does a Single node of SQL Cluster includes MsgBox and ManagementDB or are they on different Server?
4. What is the ideal setup of Sql DB? Eg: a different for MsgBox, Management DB, SSO etc?
5. Also, as per my understanding, for high availabilty we should have a BizTalk cluster, Sql cluster and SSO cluster? Is that correct?
Thanks.

Cluster or Not, all BizTalk Servers are configured in the same group and use the Master SSO instance. Only in the case of a cluster the associated DB's are clustered. Does not really change anything w.r.t configuration of the BizTalk Group.
I would refer you to the following links
http://msdn.microsoft.com/en-us/library/aa373130(v=vs.85).aspx and
http://technet.microsoft.com/en-us/library/cc757731(v=ws.10).aspx to get a better understanding of clusters. Clusters in Microsoft are a shared resource so to answer your question, the passive node will (in case of failover) get access to the resources
which were with the active instance and thus no further configu sync is required. Its is the same information from the drives, master DB, services, registry which fails over onto the passive node.
How you utilize the two (or more) nodes of the cluster depends on the load you expect to handle. You may choose to split databases across the TWO nodes [called Active/Active in Microsoft parlance]. This way BOTH the nodes have to be licensed. Each BizTalk
Database has different needs w.r.t frequency of reads/writes, size, etc. The BizTalk Performance Optimization Guide @http://msdn.microsoft.com/en-us/library/ee377064.aspx in addition to best
Practices for Maintaining BizTalk Database @http://msdn.microsoft.com/en-us/library/gg634566.aspx should provide you with guidance on how to split the BizTalk Databases across multiple cluster
nodes.
I would like to provide you ONE configuration fits all BUT that is not possible. The setup of the SQL is highly dependant on the load you expect to address through BizTalk, the HA/DR consideration pertaining to availability/licensing, etc. In short it is
a topic for an infrastructure architect.
BizTalk Cluster is again a subject of requirement. There is no BizTalk Cluster per-se, BizTalk Services (BTSNTSvc.exe) can be clustered so implying that specific host instance can be clustered. As a rule one should only look at clustering those Receive
Protocols which need to be configured for availability. Examples would be FILE, FTP, even DB locations. IIS/Web Services provide HA + scalability through NLB. If you have a SQL Cluster then it is recomended to also cluster SSO on the same set of servers primarily
because it does not require additonal BizTalk Licensing.
Regards.

Why Clustering

Hi,
          We are in the process in making our decision whether we should
          use clustering or not, to achieve our high scalable need.
          what we are planning is, run weblogic in multi-jvm environment
          without having any knowledge about each other. FYI, we are having
          one dedicated WL server to cater data access layer and data
          caching, which will allow us to achieve persistence integrity. we will be
          using Toplink for WL.
          I have few basic question regarding clustering:
          1) Why should I use clustering ?
          2) What WL clustering buy me ?
          3) What I will loose if I will not use weblogic clustering?
          4) Is Scalability is the only factor people use clustering?
          Any help/pointer is highly appreciated.
          Thanks in advance
          Ahimanikya Satapathy
          OrderCare.Com


What you mentioned is something like clustering. It seems you are saying
          that you can just run many boxes/web-logic and that is fine. The problem is,
          if each of those servers has its own non-clustered weblogic running, then
          all the sessions stored on that server get lost if the server dies. Even if
          you can load-balance among many individual non-clustered web-logics, you
          wont be able to "share" the state of the session data amongst the other
          running servers. Clustering makes sure (through memory) that if server A has
          sessions, it looks for a "buddy" server to copy that session information to.
          So it finds server b. Now A and B have the identical http session
          information (assuming we are talking front-end side). If Server A dies,
          server B takes over and thus your clients don't lose everything they had
          entered (talking JSP pages, javabeans, session scope stuff, etc). So, if you
          have a cart system that people on your site add to the cart, or a multiple
          page "wizard like" form that uses the same one bean across the pages (or
          not), if that server dies, their info is still in memory on another weblogic
          server. Even better, if one of the two servers dies, the remaining server
          located another server (if you have 3 or more running) and then replicates
          its session data out to that server..so it automatically "fails over" for
          you incase one dies.
          Hope that helps a little bit.
          "Ahimanikya Satapathy" <[email protected]> wrote in message
          news:[email protected]...
          > Thanks Wei,
          >
          > I think the answer is not that simple and it does not convince me, I can
          > achieve load-balancing,failover, performance, availability,scalability in
          > other means say for example, I can have multiple weblogic running on
          > multiple powerful boxes to achieve all the factors. so how weblogic
          > clustering helps me in this regard, where it stands ?? I would appreciate
          if
          > I would get in depth answer. Also if any body know some good documentation
          > where I can find a good argument for why clustering , will be a great
          help.
          >
          > -- Ahimanikya
          >
          > Wei Guan wrote in message <[email protected]>...
          > >For all your questions, load-balancing, failover, performance,
          > availability,
          > >scalability, etc are the answers.
          > >
          > >--
          > >Cheers - Wei
          > >
          > >
          > >
          > >Ahimanikya Satapathy <[email protected]> wrote in message
          > >news:[email protected]...
          > >> Hi,
          > >>
          > >> We are in the process in making our decision whether we should
          > >> use clustering or not, to achieve our high scalable need.
          > >>
          > >> what we are planning is, run weblogic in multi-jvm environment
          > >> without having any knowledge about each other. FYI, we are having
          > >> one dedicated WL server to cater data access layer and data
          > >> caching, which will allow us to achieve persistence integrity. we will
          be
          > >> using Toplink for WL.
          > >>
          > >> I have few basic question regarding clustering:
          > >>
          > >> 1) Why should I use clustering ?
          > >>
          > >> 2) What WL clustering buy me ?
          > >>
          > >> 3) What I will loose if I will not use weblogic clustering?
          > >>
          > >> 4) Is Scalability is the only factor people use clustering?
          > >>
          > >>
          > >> Any help/pointer is highly appreciated.
          > >>
          > >>
          > >> Thanks in advance
          > >>
          > >> Ahimanikya Satapathy
          > >> OrderCare.Com
          > >>
          > >>
          > >>
          > >
          > >
          >
          >

Are clusters thread safe?

If one thread assigns a new value to a cluster while another thread reads it via a local variable, could the reading thread get part of the old value and part of the new value? Or are cluster operations atomic?
Does this behavior- whatever it is- apply to cRIO FPGA and controller platforms as well as desktop systems? Does it apply in multiprocessor systems?
Thanks,
-Ron

tst wrote:
When you have a UI control, writing to it or reading to it will be done in one atomic operation, so reading from the control you won't get half of the old values and half of the new values.
However, as Jeff mentioned, this is a good way to create race condition and is usually a sign of trying to use LabVIEW as you would C. There are better ways to handle data.
Here's a made-up example. I'm not interested in a specific solution to this problem; I'm interested in the general question of clusters' atomicity in multithreaded or multiprocessing environments.
Suppose I have a thread that monitors a serial GPS unit and derives two values: a floating point time correction, in seconds (GPS time - platform time), and a boolean indicating whether the GPS unit is providing a good signal, i.e. whether the time correction is valid. This thread stores these values in a cluster using Bundle by Name, so in theory both values are stored at the same time. This thread writes to the cluster, but does not read it.
The other threads (or however LabVIEW divides up the processing) read this cluster using Unbundle by Name, so in theory each thread reads both values at the same time. These other threads do not write to the cluster. It is not critical that all the threads read the same values from the cluster, but it is critical that each thread reads the boolean that agrees with the float it reads, i.e. that the thread doesn't read an invalid time correction and think it's valid.
It sounds like you're saying that this does in fact work, even if the threads are running on different cores. Is my understanding correct? I realize I can play it safe and use a semaphore. I'm just wondering if I need to.

Oracle9iAS R2 - Virtual Hosts with Portal and SSO with OIDDAS application

Hi!
I have installed a the machine with name minsk.discover.local. The machine have installed Infrastructure and Portal. The instalation is sucessfull and i work fine. But i have publish Portal to WEB with name intranet.discover.com.br. The Oracle describe:
1 - Create the virtual hosts in SSO and PORTAL - OK
2 - run ptlasst to create SSO Partners Applications - OK
After this steps iwork fine with Portal and SSO, but when i click in portlet to create user to access the application OIDDAS, the Portal redirect to login page of SSO in address mct.com.br, the internal name, when then name not responde in the internet.
I need a help!!!!
Marcio Mesti

I just spoke to the Oracle App server admins, the two servers in question are clustered.
So my question changes slightly to:
What is the best way to install and configure a webgate for clustered Oracle App servers with mulitple virtual hosts, that are residing behind a load balancer (Traffic Manager)?
Thanks,
Andy

Session State Replication of Referenced Objects

Here is question on Clustering and Session state replication:
          Scenario:
          Consider two Session Objects A and B.
          Object A has-a reference to object B.
          So whatever changes done to Object B is reflected in Object A.
          In-memory Session replication happens on every HttpSession.setAttribute() call.
          The question is will the two session objects(A and B) be replicated to the other cluster and will still maintain the reference relationship or will they be two separate objects with same data (in different memory locations).
          regards,
          Jaiganesh

Ok, I have been meaning to dig into session replication in a bit more detail and your question is a good excuse to do it!
          First stop the docs:
          Bea Docs
          The bits that jump out are under:
          Programming Considerations for Clustered Servlets and JSPs
          1) Session Data Must Be Serializable, so both your objects are serializable.
          2) Use setAttribute to Change Session State In an HTTP servlet that implements javax.servlet.http.HttpSession, use HttpSession.setAttribute (which replaces the deprecated putValue) to change attributes in a session object. If you set attributes in a session object with setAttribute, the object and its attributes are replicated in a cluster using in-memory replication. If you use other set methods to change objects within a session, WebLogic Server does not replicate those changes. Every time a change is made to an object that is in the session, setAttribute() should be called to update that object across the cluster.
          Likewise, use removeAttribute (which, in turn, replaces the deprecated removeValue) to remove an attribute from a session object.
          >Will the reference as shown in the step 3 will be >maintained after replication on the other cluster ?? I >guess not!!
          I don't understand "on the other cluster" There is normally one cluster made up of a few servers. The session state is maintained on one primary server and a secondary server. So you have aObj.a2 = bObj, from the docs I would understand that at the momment you called session.setAttribute the aObj and all its fields provided they are seriliazable will be replicated in Mememory.
          >There the aObj and bObj stored in the two different >session objects will not have a reference relationship >in other words if i change bObj on the other cluster >will the reference a2 of aObj be able see it ??
          This is testing the limits of my understanding, but would have thought if the objects are in different sessions they should not be able to reference each other in the manner I think you are suggesting, so if I access aObj.a2 (an instance of bObj) and changed it in one session it should not affet any other bObj unless bObj is a singleton....I think!
          What say you?

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