Hardware Load balancing at HTTP Layer in Apps Contd..

If you are accessing this page directly without reading previous post about load balancer & broad level steps of configuring load balancer in Apps then first check previous posts mentioned at bottom

After configuring Load Balancer in Oracle Applications 11i you as Apps DBA need to apply three prereq. patches

Patch 3175852 – This patch will give tags in CONTEXT file ( xml file) required to configure load balancer , I’ll discuss on these tags in this post later
Patch 3077386 – This is for logout issue which is not function properly
Patch 3209878 – Only if you are using Oracle Configurator

If you are on apps 11.5.10 or above , these patches are already included .

After these patches you need to clone from existing tier to one more middle tier ( If existing middle tier include Concurrent Manager & Reports Node , don’t configure target instance for CM or Reports as I suppose you don’t want to configure PCP more coming on PCP in future posts you just need load balancing on HTTP Layer). I suppose you are already aware that while running adcfgclone.sh steps you can define what services you want to run on particular nodes

At this stage your node1 & node2 should be similar & users should be able to login from node1 or node2 ( http://node1.domain:port and http://node2.domain:port resp.) with their own hostnames . If this is working then lets proceed with Load balancer configuration.

Change your context file (xml file ) under $APPL_TOP/admin via context editor or OAM (Oracle Application Manager )
Before changing lets understand what variables you need to change & what each parameter mean

webentryhost oa_var=”s_webentryhost” : Change this from node1 to loadbalancer name in our case its lbr
webentrydomain oa_var=”s_webentrydomain” : Change it to load balancer domain name
webentryurlprotocol oa_var=”s_webentryurlprotocol” : Change it to protocol you use to access application http or https
activewebport oa_var=“s_active_webport” : Change it to port on which load balancer is listening . Lets assume your node1 & node2 webserver is listening on port 8000 and you want URL like http://lbr.domainname.com that means your load balancer is listening on default http port i.e. 80 so define here s_active_webport as 80

After changing these parameters on node1 , run autoconfig after changing above parameters in context file. Start your applications on Node1 only (shutdown services on node2 which is not yet configured for loadbalancer)

Try to access applications via load balancer , if you can good job (You still have to configure second node).

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If you can’t nothing to worry (It happens) How to figure out problem & where to check for issues , wait for my updates till tomorrow ….

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Tip: Don’t forget to take backup before making all these changes 😉

About the Author Atul Kumar

Oracle ACE, Author, Speaker and Founder of K21 Technologies & K21 Academy : Specialising in Design, Implement, and Trainings.

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5 comments

fhasweh says September 12, 2006

dear atul,
my users are able login from node1 or node2 ( http://node1.domain:port and http://node2.domain:port
but from node2 when we click on responsibley it alwasy go to node1 is this correct? if yes then there is no HA concept here becase if node1 is down no one will be able to use the application.

thanks
fadi

Atul Kumar says September 12, 2006

Fadi,
Do let me know how you have configured ? Do you have hardware load balancing with session persistance ( Sticky Bit )

I there any Profile option configuration at Server,Site or responsibility level.

I suppose by default all jserv on node1 & nod2 is load balanced .
Is it always from node2 requests going to nod1 ?

What if you shutdown node1 ( can you still access applications via nod2 ? )
If not do let me know how you have configured load balancing in Apps .

Atul

Atul Kumar says September 13, 2006

Fadi,
Issue is because profile option “ICX Forms Launcher…” at site level is set to Node1 thats why all hists from node2 for forms session are going to node1 .

You can set “ICX form launcher…” profile level option at server level at server node2 pointing to Node2 . That way forms session from node2 will aunch from node2

Do let me know if this doesn’t fix your problem

Atul
http://teachmeoracle.con
Atul

M Ashour says February 14, 2008

Hello ,
Is it mandatory to use session persistence ( Sticky Bit) load balancer,or we can use non session persistence as well?
BR

Atul Kumar says February 16, 2008

BR its compulsory to set session persistence because if client goes to one server and after that goes to another server then it will prompt user to login again as user session cookie won’t be at server

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