Java EJB Interview questions Part9

Question: What is Vertical Scaling?

Answer: When multiple server clones of an application server are defined on the same physical m/c, it is called Vertical Scaling. The objective is to use the processing power of that m/c more efficiently.

Question: What is Horizontal Scaling?

Answer: When Clones of an application server are defined on multiple physical m/c, it is called Horizontal Scaling. The objective is to use more than one less powerful m/c more efficiently.

Question: What is a Server Group?

Answer: A server group is a template of an Application Server(and its contents) i.e, it is a logical representation of the application server. It has the same structure and attributes as the real Application Server, but it is not associated with any node, and does not correspond to any real server process running on any node.

Question: What is a Clone?

Answer: The copies of a server group are called Clones. But unlike a Server Group Clones are associated with a node and are real server process running in that node.

Question: What is Ripple Effect?

Answer: The process of propagating the changes in the properties of a server group during runtime to all the associated clones is called Ripple Effect.

Question: What level of Load Balancing is possible with EJBs?

Answer: The workload management service provides load balancing for the following types of enterprise beans

1. Homes of entity or session beans

2. Instances of entity beans

3. Instances of stateless session beans

Question: What is the basic requirement for in-memory replication in Weblogic?

Answer: 1. The data in session should consist only of Serialized objects.

2. Only setAttribute function should be used to set objects in session

Question: How JDBC services can be used in clustered environment?

Answer: Identical DataSource has to be created in each clustered server instances and configure to use different connection pools.

Question: What are the services that should not be used in a Clustered Environment?

Answer: Non-clustered services:

1. File Services

2. Time services

3. Weblogic events

4. Weblogic Workspaces (In WebLogic 5.1)

Question: Mention some tools to cluster Web Servers?

Answer: Web Servers can be clustered using

1. Edge Server.

2. DNS