WebSphere Job Interview Sample Questions 001

What is a virtual host?

Virtual hosting is a method for hosting multiple domain names on a computer using a single IP address. You can use admin console environment > virtual host to modify alias and assign port numbers (alias plus port numbers = virtual host)

 

How do you configure JDBC and JMS resources?

• First create a JDBC provider (a JDBC provide encapsulates the JDBC driver for a specific database). From the admin console Resources > JDBC Providers. 
• Then, create and configure the datasource that is associated with the proper JDBC provider. The datasource is the connection that the Java application uses to connect to the database. Resources > Data Sources are the panels to use in system configuration. 
• Be particular consistent with the JNDI name of the data source. The JNDI is used in the Java application to access the database
• Type 2 driver - you need client - Type 4 driver - pure Java 
• For Type 4 Driver, you will need
• server name
• database name
• port number
• authentication mechanism along with security credentials (for example, username and password, authentication - JAAS) 

• Connection pool - performance consideration - max and min connection size

•  Configure MQ JMS provider
• Configure Connection Factory and but very careful about the JNDI name because that it what the developers will use (to create sessions and then, consumers or providers) (binding mode with the local MQ queue manager or client mode where a client connection is needed to connect to a remote queue manager)
• Then, create queue or topic
• Finally, you have to configure the listener port to connect the dots

Click on the picture to see a very clear picture

• WebSphere Application Server > Communication > Messaging > Listener Port > New
• The most important items are Connection factory JNDI name and Destination JNDI name  these form the connection between the MDB, its connection to listen to and the destination for its messages  

What are the steps involved in deploying an application?

• Make sure that the resources needed by the application are configured correctly such as JDBC, JMS, virtual host, among others
• The ear file is readily available on a local or remote server
• Use Application Panel of the admin console and choose new and follow the prompts
• Recycle the server and perform post installation certification
• Use web.xml to determine the context root and home page for testing - the following is the directory to look for the file -
• C:\Program Files (x86)\IBM\WebSphere\AppServer\profiles\AppSrv04\installedApps\DOD02Node03Cell\ivtApp.ear\ivt_app.war\WEB-INF

What is session persistence? What mechanisms does Websphere have for session persistence?

Session persistency is option to recover the session data in case the server crashes or the session data is too valuable to lose. There are two ways to configure session persistency - database or memory to memory replication. The memory to memory replication has better performance and the database approach is more reliable. JSESSION ID is the server side artifact supporting session and prefer local session affinity are both good topics.

Have you used wsadmin? What are the different objects available in wsadmin?

• AdminControl - deal with MEAN that represent live object
• AdminConfi - deal with configuration stored in the configuration repository
• AdminApp - update application metadata
• AdminTask - used to access a set of task-oriented administrative commands that provide an alternative way to access the configuration commands
• Help - print Help.AdminControl() - this gives you a list of the objects. If you want to read text about each area, you can use AdminControl.help()

Troubleshooting – give couple of scenarios where you were involved in troubleshooting

• JVM crashes with memory exhaustion - caused by application logging logic failure and unbounded data structure to hold business records to log 
• Ear files disappeared without obvious cause - WAS Virtual Enterprise anomaly - system automatically reinstalled application under certain circumstance - suspicion autonomic computing error
  

Monitoring tools – TPV, Introscope – have you used them?

• TPV for light weight monitoring and performance tuning
• Introscope dives deep into WAS and the application in the JVM
  

Describe the most complex topology you have worked with

• KTC
• CHS
  

Some basic UNIX commands, flavors of UNIX you have worked on.

• Ultrix - coding - socket, pipe, broadcasting, multicast, distributed large scale cashing
• Sun Solaris 9
• AIX 6
• Red Hat LINUX 9
• Ubuntu 10