WAS interview questions:
Compare the WAS process server & WAS portal server and WAS application server?
Process server is a high performance business engine that executes mission critical business processes more securely and consistently.
Portal Server: built on WAS, used to execute portlets. A portal is a composite application that is assembled at the front-end. It is an aggregation point for services delivered through portlets. This new feature in WebSphere Portal V6 makes it easier for end-users to use and to customize the portal to interact with services that they need.
App Server: which is used to execute the J2EE applications, supports load balancing, work management etc.,
Compare Version V.5 and V6? In v5
we don’t have a profile concept, where as in v6 we can create 3 types of profiles by which we can create number of servers without installing the product binaries again and again. And also v6 supports web services.
What is profile ? How many types of profiles u have? In v6 we have 3 profiles: Dmgr, Stand-alone and Custom. In v6.1 there is one more extra profile called cell profile, which is a combination of Dmgr and stand-alone profile which is already federated to it.
What is SIB’s? Service integration bus supports applications using message-based and service-oriented architectures. A bus is a group of one or more interconnected servers or server clusters that are members of the bus. Applications connect to a bus at one of the messaging engines associated with its bus members. By default, the SIB Service is disabled. This means that when a server starts it does not have any messaging capability. The SIB Service is automatically enabled when you add the server to a service integration bus. You can choose to disable the service again by configuring the server.
What is the command to find out the WAS version?
versionInfo
How many types of containers are there in WAS, and what is the role of those containers?
Two types of containers: web container and EJB contianer
Web container: used to execute the requests related to servlets, jsp’s html etc.,
EJB container: used to execute EJB applications. This will contain 3 types of beans (session, entity and MDB beans).
How did u differentiate b/w static and dynamic content?
Static website is where we can not change the content until next edition.
A dynamic website on the other hand uses programming in addition to the layout to not only allow the flow of data in and out of the site but to make meaningful relationships with the data.
How many types of clusters WAS support? What did u meant by Horizontal & vertical ?
Two types of clusters:
A vertical cluster has cluster members on the same node, or physical machine.
A horizontal cluster has cluster members on multiple nodes across many machines in a cell.
Can you give the scenario when we will go for horizontal & vertical clustering ?
Suppose if our organization is having servers in diff locations, and if we want to manage them than we will create horizontal cluster. If all the servers and in the same location than we will use vertical cluster.
How to apply the fix packs?
Ans: we need to stop all the JVM instances than apply the fix pack.
Due some reasons nodeagent was not running? Where did u check for the logs?
We need to check the nodes logs (startNode.log)
Addnode full command?
app_server_root/bin/addNode host_name soap_port -includeapps
efaults ports for SOAP, admin, Bootstrap? SOAP: 8880, admin: 9060, bootstrap:
What is virtual host?
A virtual host is a configuration entity that enables a single host machine to resemble multiple host machines. It maintains a list of Multipurpose Internet Mail Extensions (MIME) types that it processes. You can associate a virtual host to one or more Web modules, but you can associate each Web module with one and only one virtual host. Resources associated with one virtual host cannot share data with resources associated with another virtual host, even if the virtual hosts share the same physical machine.
What is the role of node agent?
Node agents are administrative agents that represent a node to your system and manage the servers on that node. Node agents monitor application servers on a host system and route administrative requests to servers.
What is cell?
A cell is a configurational concept which is used to administer the processes in that particular cell by using Dmgr.
Do we have any unmanaged node in a cell?
Yes we can have an unmanged node in a cell, and these unmanaged nodes are maily useful to define web servers.
How do u configure a datasource.
servers > Application servers > server_name > Web container settings > Session management > Distributed environment settings > Database.
Here we need to configure the datasource details.
Which command u used to find out the IHS version?
What all information we can get from the plugin-cfg.xml file?
Plugin.xml file:
A plug-in is described in an XML manifest file, called plugin.xml, which is part of the plug-in deployment files. The manifest file tells the portal application’s runtime what it needs to know to register and activate the plug-in. The manifest file essentially serves as the contract between the pluggable component and the portal application’s runtime
What is the command to find out to run the process?
What is the command to find out the ports, which are listening on box?
Netstat -an
appplication server vs webserver
application server is used to execute the j2ee applications where as web server is used to execute the requests related to servlets, jsp’s and html. And web servers also used to route the request to diff app servers.
Why we require web server separate:
The Web servers are necessary for directing traffic from browsers to the applications that run in WebSphere Application Server. It is mainly used for the router for directing the request between different application servers which are in cluster. The Web server plug-in uses the XML configuration file to determine whether a request is for the WebSphere Application Server.
how user request will process
First the request will go to web server, there the plug-in will decide to which app server it should go. Then the request will go to the particular app server, then the request can move to DB(if requires).
What is the usage of plug-in?
The plugin-cfg.xml file will contain all the applications information and servers and their ports information. This information is used to direct the request to the available server.
EAR vs WAR vs RAR
EAR, enterprise archive, which is the combination of WAR, JAR and RAR files. And this is the file we will deploy it on to the app server for execution.
WAR, web archive, which will contain all the servlets, jsp’s and html things, which will make up this web module.
RAR, resource adapters, it will contain the connections to all the external resources.
What is mean by clustering?
Clusters are groups of servers that are managed together and participate in workload management. A cluster can contain nodes or individual application servers.
Installation procedure
cd_root/operating_system/architecture/ifpackage/WAS/install, by clicking install.sh here we can install the WAS onto Unix box.
Data Source
Data sources allow you to manage a pool of connections to a database.
Data sources work as follows:
When a client wants to use a connection, it looks up a data source by name from a JNDI server.
The data source then returns a connection to the client.
If the data source has no more connections, it may ask the database manager for more connections (as long as it has not exceeded the maximum number of connections).
When the client has finished with the connection, it closes the connection.
The data source then returns the connection to the available pool.
Data Source creation
We can create a datasource in one of two ways:
Resources > JDBC > Data sources > data_source
Resources > JDBC > JDBC providers > JDBC_provider > Data sources > data_source
ND vs Base
No profile concept in base where as we can create no. of servers by using a profile concept which is available in ND. That will reduce the installation space.
Directory structure
Important configuration files
Wimconfig.xml – stores the vitual member manager global settings.
Use the ssl.client.props file to configure Secure Sockets Layer (SSL) for clients. In previous releases of WebSphere Application Server, SSL properties were specified in the sas.client.props or soap.client.props files or as system properties.
To configure the IBM HTTP Server, edit the httpd.conf configuration file.
We should update the was.policy file if the application has specific resources to access.
JVM setting
The JVM translates the Java byte codes into the native instructions of the host machine. The application server, being a Java process, requires a JVM in order to run, and to support the Java applications running on it. JVM settings are part of an application server configuration.
To view and change the JVM configuration for an application server's process, use the Java virtual machine page of the administrative console or use wsadmin to change the configuration through scripting.
Procedure :
In the administrative console, click Servers > Application Servers >server. Then, under Server Infrastructure, click > Java and Process Management > Process Definition .select Java Virtual Machine.
Specify values for the JVM settings as needed and click OK
What is heap dump?
Although heap dumps are generated only in response to a detected memory leak, you must understand that generating heap dumps can have a severe performance impact on WebSphere Application Server for several minutes.
Federation:
Federation is the process of adding profiles to Dmgr. This can be done in 2 ways: By using the Dmgr’s admin console or by using the command prompt. In both the cases we need to specify the SOAP port info.
Configuration backups
We can take configuration backups by using “backupConfig” command.
Application maintenance
what is dmgr
Dmgr is one type of profile which is used to administer the different profiles which are federated to it, and also can be able to mange webservers which are defined on a managed node. On this profile we can’t deploy any applications, it’s just central management tool.
wsadmin main commands
AdminControl: Use to run operational commands.
AdminConfig: Use to run configurational commands to create or modify WebSphere Application Server configurational elements.
AdminApp: Use to administer applications.
AdminTask: Use to run administrative commands.
Help: Use to obtain general help
In which file all the ports entries are there? server.xml
thread dump
The JVM creates a thread dump whenever an application server process spontaneously closes. You can also force an application to create a thread dump. After a dump is created, you can check the dump for clues as to why new requests are not being processed
After the application creates the dump, you can check for the following clues:
Look for an excessive current heap size. The thread dump shows information on the current Java heap size, and the minimum and maximum heap size settings.
Look at the snapshot of each thread in the process. The thread dump contains a snapshot of each thread in the process, starting in the section labeled "Thread Information."
Look for threads that are waiting on locks held by other threads.
Look for multiple threads in the same Java application code source location. Multiple threads from the same location might indicate a deadlock condition (multiple threads waiting on a monitor) or an infinite loop, and help identify the application code with the problem.
Name of plgin logfile?
For every plugin we need to mention the log file location and name in the plugin-cfg.xml file. Then in that specified file the logs will be stored.
What is core group?
A core group is a high availability domain that consists of a set of processes in the same cell that can directly establish high availability relationships. Highly available components can only fail over to another process in the same core group and replication can occur only between members of the same core group.
How IHS and WAS talk to each other?
By using the plug in configuration file.
What type info can u see in plugin file?
Plugin.xml file is a part of the plug-in deployment files. The manifest file tells the portal application’s runtime what it needs to know to register and activate the plug-in.
WebSphere Application Server functions use information in this file during the configuration and deployment phases of Web application development.
What si the command to find out version of IHS?
./apachectl -v
Log files in IHS?
Access.log and error.log
Nohup: No Hang Up. Runs a command even if the session is disconnected or the user logs out.
Run a command immune to hangups, runs the given command with hangup signals ignored, so that the command can continue running in the background after you log out.
SYNTAX
nohup Command [Arg]...
nohup command
Answer is simple, use nohup utility which allows to run command./process or shell script that can continue running in the background after you log out from a shell:
Syntax:
nohup command-name &
Where,
Command-name: is name of shell script or command name. You can pass argument to command or a shell script.
&: nohup does not automatically put the command it runs in the background; you must do that explicitly, by ending the command line with an & symbol
Log levels: Off, Fatal, Severe, Warning, Audit, Info, Config, Detail, Fine, Finer, Finest, ALL.
Log location
Main log files will be available at /root/bin/logs dir. And for individual processes they will be available in their own /bin directories.
Log information
By using the information in the log files we can know the status of the operation that we are performing
how we will configure WAS with IHS?
By using the plugin conf file (plugin-cfg.xml).
What is security colobrator?
DumpNamesSapce
You can use the dumpNameSpace tool to dump the contents of a name space accessed through a name server. The dumpNameSpace tool is based on Java Naming and Directory Interface (JNDI).
Eg: dumpNameSpace -host myhost.mycompany.com -port 901
Name space dump output is sent to the console. It is also written to the file DumpNameSpace.log in the server's log directory
FFDC:
The first failure data capture (FFDC) log file saves information that is generated from a processing failure. These files are deleted after a maximum number of days has passed. The captured data is saved in a log file for analyzing the problem
FFDC instantly collects events and errors that occur during the WebSphere Application Server runtime.
Activity. Log/Service Log
The IBM service log contains both the WebSphere Application Server messages that are written to the System.out stream and some special messages that contain extended service information that can be important when analyzing problems. There is one service log for all WebSphere Application Server Java virtual machines (JVMs) on a node, including all application servers and their node agent (if present). A separate activity log is created for a deployment manager in its own logs directory. The IBM Service log is maintained in a binary format. Use the Log and Trace Analyzer or Showlog tool to view the IBM service log.
The Java virtual machine (JVM) logs are written as plain text files. The JVM logs are created by redirecting the System.out and System.err streams of the JVM to independent log files. WebSphere Application Server writes formatted messages to the System.out stream. Systemout.log and Systemerr. Log are the two files for JVM logs.
Process logs / native logs
WebSphere Application Server processes contain two output streams that are accessible to native code running in the process. These streams are the stdout and stderr streams. Native code, including Java virtual machines (JVM), might write data to these process streams
Garbage Collection: The Java run-time system performs garbage collection automatically. It finds memory that a program is no longer using and frees it. In the Profiling Tool, garbage collection can only be run if the process is active. Garbage collection is available from Memory Statistics view
We can enable this option by going to application servers->server1->process definition->Java virtual machine, than select the option “verbose garbage collection”
Can u control GC cycle? How do u control that?
LOGSJVM logs (SystemOut and SystemErr)
1. You can find the logs in the following directory:
<WAS_install_root>/profiles/<profile>/logs/<process
2.from the administrative console, select
Troubleshooting → Logs and Trace. Select the process whose logs you want to configure, and then click JVM Logs. The General Properties window opens.
3.Your applications can also write to them by using the print(), println(), and
printStackTrace() methods.
4.SystemOut and SystemErr logs are created for every WebSphere® Application
Server process (application server, cluster member, node agent, and deployment manager).
First Failure Data Capture (FFDC)
1.The FFDC feature runs in the background and collects events and errors that occur during WebSphere Application Server runtime and processing failure.
2.The information that it collects are written to log files in the
<WAS_install_root>/profiles/<profile>/logs/ffdc directory.
3.There are three FFDC configuration files in the <WAS_install_root>/properties directory ffdcRun.properties, ffdcStart.properties, andffdcStop.properties.
Process (native) logs
1.On execution of Native code these logs are generated. Native code is non-Java code,typically found in files with .dll, .exe, and .so extensions.
2.The process logs are named native_stdout.log and native_stderr.log
3.They are located in the <WAS_install_root>/profiles/<profile>/logs/<server> directory
service log (activity.log)
1) The activity.log and is found in the
<WAS_install_root>/profiles/<profile>/logs directory 2)There is only one activity.log for each node
3)WebSphere Application Server runtime events are logged to the activity.log
4) It is written in binary format, so it cannot be viewed in a
text editor. The main purpose of the activity.log is that it can be viewed with the
Log Analyzer tool, is a graphical user interface that displays the events from the activity.log and uses a symptom database to analyze the events and diagnose problems
Installation Logs:
1)<WAS_install_root>/profiles/<profile>/logs/pctlog.txt
This log file records the profile creation status
2)Enable trace logging in the Web server plug-in by setting the LogLevel directive
in the plugin-cfg.xml file as shown
<Log LogLevel="Trace"
Name="c:\ibm\was6\plugins\logs\webserver1\http_plugin.log" />
3)This example also shows you where you set the amount of
detail that is logged.
<Log LogLevel="Error"
Name="c:\ibm\was6\plugins\logs\webserver1\http_plugin.log" />
4) Output from wsadmin
Messages from wsadmin are written to the wsadmin.traceout log file:
<WAS_install_root>/profiles/<profile>/logs/wsadmin.traceout
You can also increase the amount of data that is logged to this file by tracing the
wsadmin utility. To do so, update the following file:
<WAS_install_root>/properties/wsadmin.properties
Uncomment the following line:
com.ibm.ws.scripting.traceString=com.ibm.*=all=enabled
5)Management scripts like startServer.log, stopServer.log, startManager.log etc generated when we run respective .sh(script files) into log directory.
Ex. Location: <WAS_install_root>/profiles/<profile>/logs/<server>/stopServer.log
6)The profile creation and management tool wasprofile writes messages to the
profile independent logs directory, that is:
<WAS_install_root>/logs/wasprofile/<profile>.log
ADMIN CONSOLE
1)As you work with the configuration, the original configuration file and the new
configuration file are stored in a folder at:
<profile_home>/wstemp
Once you save the changes, these files are removed from the wstemp folder.
2)To change the admin console time out
1. Copy the following script into a file.
Example 4-1 Jython script to change the console session expiration
dep = AdminConfig.getid("/Deployment:isclite/" )
appDep = AdminConfig.list("ApplicationDeployment", dep )
sesMgmt = AdminConfig.list("SessionManager", appDep )
# check if existing sesMgmt there or not, if not then create a new one, if
# get applicationConfig to create new SessionManager
appConfig = AdminConfig.list("ApplicationConfig", appDep )
if (appConfig == ""):
# create a new one
appConfig = AdminConfig.create("ApplicationConfig", appDep, []
)
# then create a new SessionManager using new Application Config
just created
sesMgmt = AdminConfig.create("SessionManager", appConfig, [] )
else:
# create new SessionManager using the existing
ApplicationConfig
sesMgmt = AdminConfig.create("SessionManager", appConfig, [] )
#endElse
#endIf
# get tuningParams config id
tuningParams = AdminConfig.showAttribute(sesMgmt, "tuningParams" )
if (tuningParams == ""):
# create a new tuningParams
AdminConfig.create("TuningParams", sesMgmt, [["invalidationTimeout",
<timeout value>]] )
else:
#modify the existing one
AdminConfig.modify(tuningParams, [["invalidationTimeout", <timeout
value>]] )
#endElse
# saving the configuration changes
AdminConfig.save()
142
2. Change the <timeout value> on the two lines of this sample to the new
session expiration value. This number specifies the number of minutes the
console preserves the session during inactivity.
3.Save the file to any directory using, for example, the filename timeout.py.
4. Start the wsadmin scripting client from the
<was_home>/profiles/<profile_name>/bin directory.
5.Issue the following command.
wsadmin -f <path to jython file>/timeout.py
SERVER
1)Changing the working directory
of server
a) Select the server
b)Expand the Java and Process Management
c)select Process Definition.
d)change the working directory from
${USER_INSTALL_ROOT} to
${PLANTSBYWEBSPHERE_ROOT}/workingDir
2)To create server virtual host, do the following
1.Select the Environment → Virtual Hosts entry in the navigation pane.
2.Click New.
3.Enter the virtual host name, plantsbywebsphere_host.
4.Click Apply.
5.Select Host Aliases in the Additional Properties section.
6. Add the two aliases by clicking New, entering the
values, and clicking OK.
3)Creating virtual hosts is done using the VirtualHost directive, as in Example 14-2.
Example 1 Using VirtualHost
<VirtualHost www.plantsbywebsphere.com:80>
ServerAdmin webmaster@plantsbywebsphere.com
ServerName www.plantsbywebsphere.com
DocumentRoot "C:\IBM\HTTPServer\htdocs\plantsbywebsphere"
ErrorLog logs/plantsbywebsphere_error.log
TransferLog logs/plantsbywebsphere_access.log
</VirtualHost>
SIB
service integration bus supports applications using message-based and service-oriented architectures. A bus is a group of interconnected servers and clusters that have been added as members of the bus. Applications connect to a bus at one of the messaging engines associated with its bus members.
FIX Packs:
we need to stop all the JVM instances than apply the fix pack.
Heap &Thread Dumps:1)thread_dump.sh - Collect Thread dumps
2)_The JVM creates a thread dump whenever an application server process spontaneously closes. You can also force an application to create a thread dump. After a dump is created, you can check the dump for clues as to why new requests are not being processed.
3) After the application creates the dump, you can check for the following clues:
Look for an excessive current heap size. The thread dump shows information on the current Java heap size, and the minimum and maximum heap size settings.
Look at the snapshots of each thread in the process. The thread dump contains a snapshot of each thread in the process, starting in the section labeled "Thread Information."
Look for threads that are waiting on locks held by other threads.
00Look for multiple threads in the same Java application code source location. Multiple threads from the same location might indicate a deadlock condition (multiple threads waiting on a monitor) or an infinite loop, and help identify the application code with the problem.
Garbage Collection:
1)The Java run-time system performs garbage collection automatically.
2) We can enable this option by going to Application Servers->Server1->Process Definition->Java Virtual Machine, than select the option “verbose garbage collection”.
