Thursday, 27 March 2014

Real time issues and interview questions

what is the difference between the Generate Plug in and Propagate Plug in?

generate plugin:-if any changes are done in websphere environment then we have to do generate plugin(changes like:-change in virtual host, creating or deleting servers or clusters, deploying or deleting new application)to create the plugin we have a cmd bin/genplugincfg.bat->dmgr/bin directory) then it will be generated in the DMGR cell level.
Propogate plugin - It transfers the generated plugin to it respective remote webserver config path : <WEBSERVER_HOME>/Plugins/config.

Why can't we start nodeagent from the DMGR console when it is stopped as there is no option given to start it from dmgr console and at the same time if it is that is nodeagent is started then we can restart it from the Console ...why is it so?

node agent is a interface, communicator b/w servers and dmgr.. But there is not interface between dmgr and nodeagent. nodeagent behaves like manager to itself..once you start the nodeagent you can give commands like stop, start jvms in the similar way you can stop and restart the node agent as it is running..if nodeagent stopped, if you are issuing command like start nodeagent which process is going to receive the command.

there is restart option in console and as we know in restart the nodeagent first stops then starts..then in this case as it stops the nodeagent in restart then hw it again starts it if ur explanation is valid?

answer is simple lets take this general example. u can call a mobile if it is switch on (u can reach NodeAgent if it is running and u can do activities like stop/restart from dmgr)

u cant call a mobile if it switched off ( u cant reach Node Agent if it is stopped and u cant do any activities stop/restart/restart) so only from mobile he can switch on (so u can start Node Agent from Node Agent only)

but if mobile is reachable u can call your friend and ask him to switch off and switch on his mobile (if nodeAgent is reachable u can restart(stop+start) from dmgr )
 or
we have 'restart' option for Nodeagent in admin console. Restart is nothing but stopping and starting. When 'restart' option is clicked, NA first stops, which breaks the communication between NA and DMGR. So, how does NA start again? My understanding is DMGR, at one shot, sends both stop and start signals/commands to NA. My point here is where the start signal/command is stored when NA stops?

when we synchronize node from cmd mode, why do we need to stop nodeagent.

 To make sure no changes to the master configuration while performing full sync via cmd. If node agent Is up and some one else saving configuration which conflict to the full sync...

 if did not stop node agent, then changes made by sync is not recognize and in next auto sync all these changes are overridden. because node agent sync is done only from dmgr. so it identifies only changes known by dmgr, if u do manually sync without stopping nodeagent ,then dmgr doesn't come to know these changes and those are overridden in next sync.

How to get the password of .kdb file if we forget?

once you have create the .kdb file this file related passwords are stored into .sth file it will be stored into the same directory.in the .sth file contains the .kdb file password in encrypted format.

what all information we can find in severindex.xml file
Details of the JVM server process witin that node where the serverindex.xml belongs
Deployed Applications within that Server
The Ports which like "SOAP_CONNECTOR_ADDRESS" , BOOTSTRAP_ADDRESS etc

what are the different types of logging and troubleshooting utilities in websphere?

we have a) Trace logs
b) JVM Logs = Server logs such as sysout.log, syserror.log, nativesttd.log nativeerror.logs etc
c) webserver logs = Access.log and error.log

What is difference between jacl and jython?

Both same jacl is old one more using in market(Little bit defuilt to understand syntx etc).Jython using now in market(user understandable)

when will you regenerating the pluggin?

when we made manual changes on configurations file, at that time we will regenerate.

We have a serious problem with the DMGR admin console, cannot able to open the admin console. Manager is up nd the port number is checked nd it is fine. The same works in another environment. Can someone give few steps to fix the issue?

 backup of isc application and remove the admin console using below wsadmin then restart the dmgr may be it helps you wsadmin.bat –f deployConsole.py remove
wsadmin.sh –f deployConsole.py install

 Before removing Temp files, Stop DMGR, clean all Temp files under dmgr/temp, dmgr/wstemp & dmgr/config/temp and also check any Java process still exist on Task manager . REstart MDGR, this should set your issue


WAS855 installed with nonroot.Fixpack was installed with root.In the same system another WAS8 is installed.Now the issue is when I check or run versionInfo through root it is showing version as 855.When I check through nonroot it is showing version as 800.(Reason is that when I check thourgh "env" it is picking up WAS8 path.Even I tried to execute setupCmdLine.sh for WAS855 its not working.Manually I tried to set path for Java.Even then no use).What could be the reason and how to solve this issue

Issue got resolved by installing with root.Later changed the permissions and working fine

What is the difference between deploying an EAR File and WAR File?

in ear files no need to give the context root...in war files u have to give
1.EAR menace Enterprise application and WAR menace web application
2.In WAR Auto Deployment is possible where else in EAR auto deployment is not possible
3.WAR contains Web.xml file where EAR contain web.xml and Application.xml file

what are the steps should be taken before depolying a application in production evirnotment

first take necessary backups ,raise change request,approval request and schedule time from change control

How can we do hot deployment on PROD app servers ? App should be deployed and clustered app servers needs to recycled without an outage ?
do the deployment...and then do ripple restart...it will recycle jvm 1 by 1...no outage

Hot deployment means, adding modules or additional services to the existing or new application without stopping the app server as well as application. In your case, When application is went to PROD environment then you can't stop the application as application requests will come, so you can do hot deployment now.

If suppose dmgr having only one node in that only one JVM. If suppose dmgr &node agent of the node is also down. I want to start the JVM inside the node Is it possible or not?

 It is possible to run a JVM without running of DMGR, but without node agent is JVM will not start... !

if in case failure of DMGR node, then how do we handle the issue ?

 No impact to the severs even if dmgr is down. Only configuration changes not possible to do

 else simply kill the PID of DMGR and node agent and restart it again at the same time tail the logs any you can know the answer from the logs

how i can know how many users are hitting the application? if any command is there to find out the hit-counts?

 if i enable map stat where can i see the hit count.
 U have to check in error.log
 Using monitoring tool introscope willy

when we are accecing irctc at night time some times it shows it is under maintenance. (in realtime environment how can we set that page) i hope u got my point.

Need to add custom property of that JVM, saying under maintance.. Then if the jvm is down. It will how that message
Application server->Server->Webcontainer->Custom Properties-> New
 Add the below

Name: com.ibm.ws.webcontainer.webgroupvhostnotfound
Value: <html><head><title>UNder Maintennance</tile></head></html>

there any possibility to install all versions of WAS at a time on one OS?
you can install but need to give different file system path

Server went to hung state i have restarted to resolve the issue. but when i see in the logs I am getting below error in the logs. Please let me know how to avoid this error in future. My WAS Version is 6.1.0.31

J2CA0045E: Connection not available while invoking method createOrWaitForConnection for resource jms/XXXQCF

This most probably is the issue with not having too much of connections in the connection pool

Looks like there are no avaliable connections in the connection pool.

Either you must have set the max connections to a very low number or its not tuned to suit your application need.

The immediate fix would be bump up the max connections and then tune your connection pool settings.

In what situations we have to go through activity logs and trace logs... please explain in detail..thanks in advance
activity.log & trace.logs are available in webserver, when we are not able to communicate to the app.server we can check here...

what is the use of connection pools?


 connection pools are readymade connections to database. we can use these connection again and again. these comes with datasource creation.

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