What is Oracle SID in Database?
It is a Service ID in Oracle database, that we need to use in configuring JDBC Connection pool.
What is listener in database?
In Oracle listener is that which is associated with a SID and host, port. It is configured in the tnsnames.ora file. You can verify it by tnsping command
What are
the difference between Connection pool and data source?
"ConnectionPool is physically connects to the
Database. Whereas Data Source is a logical resource that can be used by
developer or any other resource for accessing Connection of pools.
DataSource can be associated with JNDI name that is used
for lookup from any other client."
How to
configure a DB connection pool?
Choose the DB type (Oracle, Sybase, Mysql, etc...).
Then choose the driver type for the DB.
Give the connection pool name.
Give the DB Service ID, schema name and password.
Then it will ask for testing the connection pool/DataSource.
After successful connection, it will ask you to create
and deploy the connection pool target to server or cluster. After
creating new connection pool always point the jdbcstore to the connection pool
created. This is required because A JMS JDBC store will be used for persistent
messaging.
After each JDBC connection, we have to restart the server
if there is startup classes dependancy exists otherwise no restart required in
WebLogic 9.x and higher versions.
What is
JNDI?
Java Naming and Directory Interface
Applications use naming services to locate objects data sources, EJBs, JMS, MailSessions, and so on within the WebLogic domain. A naming service associates names with objects and finds objects t3 protocol will be used. (The RMI registry is a good example of a naming service.)
JNDI provides a common-denominator interface to many existing naming services, such as LDAP (Lightweight Directory Access Protocol) and DNS (Domain Name System). These naming services maintain a set of bindings, which relate names to objects and provide the ability to look up objects by name. JNDI allows the components in distributed applications to locate each other.
The Java Naming and Directory Interface™ (JNDI) is an
application programming interface (API) that provides naming and directory
functionality to applications written using the Java™ programming language.
It is defined to be independent of any specific directory
service implementation.
Thus, a variety of directories -new, emerging, and already deployed can be accessed in a common way.
The WebLogic Server implementation of JNDI supplies methods that:
Give clients access to the WebLogic Server naming
services
Make objects
available in the WebLogic namespace
Retrieve objects from the WebLogic namespace
Java Messaging System it is a API supported by
J2EE application server for messaging between diffent resources. it can be
used by MDB (Message Driven Beans). First you need to configure JMS
System resource, JMS module consists any one out of
PTP, publisher/Subscriber type
How to configure JMS?
JMS (Java Message Service) is a standard API for
accessing enterprise messaging systems. Specifically, WebLogic JMS:
Enables Java applications sharing a messaging
system to exchange messages.
Simplifies application development by providing
a standard interface for creating, sending, and receiving messages.
Using the Administration Console, you define
configuration attributes to:
1. Create JMS servers and target a WebLogic Server
instance or a Migratable Target where the JMS server will be deployed.
2. Create and/or customize values for JMS servers,
connection factories, destinations (queues and topics), JMS templates,
destination sort order (using destination keys), persistent stores (file or
JDBC), paging stores, session pools, and connection consumers.
3. Define message and/or bytes thresholds and quotas, as well as a maximum allowable message size on your JMS servers, destinations, and templates.
Enable any desired WebLogic JMS features, such as:
Server clustering using multiple connection factories.
High availability and load balancing for destinations
across a cluster by using distributed destinations.
Persistent messages and durable subscribers.
Paging out message bodies during peak
load periods to free up memory.
Controlling message flow during peak
load periods, including blocking message producers.
Establishing a message expiration policy to ensure
that expired messages are cleaned up immediately.
Preventing message quota errors by
temporarily blocking message producers from sending messages to a destination
when it exceeds its specified maximum message quota.
Concurrent message processing via session
pools.’
What is
a domain template?
A domain template is a jar file default one is wls.jar file, which is '/bea/weblogic81/common/templates/domains/, it has all the features that is required for the standard weblogic domain, we can even create domain template of our own configuration. by this template we dont have to configure every time we create a new domain.
By using
template we can:
Create servers.
Clusters.
Machines.
Configure services such as JMS, JDBC, and Applications
What are
the Admin Default ports?
The non-SSL listen port for the Administration Server's
default network configuration is 7001 by default.
The SSL listen port for the Administration Server's
default network configuration is 7002 by default.
WebLogic Admin servers and Managed servers could
communicate with Admin port which is separate network channel. So that other
communications can be run on different networks.
Why
datasources , JMS need JNDI?
JNDI is a light weight directory which is used to lookup
from other resources. Entity EJB lookup for DataSource, Message Driven
Beans lookup for JMS. Servlets, JSP web compoents lookup
for JDBC connections for few actions. which is not recommmend in real time.
What are
the action to be taken when server is crash ?core file is not generated
what to do?
if sever is crash u cannot do anything after words :) if
u got alerts you can managed to get Heapdumps as you told.
reasonpstack, jmap, pmap requires process id.
If third party package installed in Solaris then you can
use dbx command for further investigation.
In solaries we use pstack and pmap command to take long stack and to find which thread library causes the problem instead of using debbuger.. For linux is there any command that do the same tasks..pmap is working in linux but there is no pstackcommand..after a long search i found one command which is equal to pstack ...i.e lsstack ( equal to pstack).. but it is not working...
If SSL certificates are expired what to do?
Two options:
1. Using temporary demo certificates.
2. Get new renewal from CA(Certifying Authority) like
verisign.
Basic
requirement for data source and connection pools?
Amazon.com Widgets
The Basic need for Connection Pool and DataSource are:
1. connection to the adminserver
2. JDBC Driver name, connecting parameters such as
DataSource name, DATABASE schema details (user,password, hostname, port, SID)
3. Target the connection pool to a 'server' or 'cluster'.
4. Finally verify the connection pool by testing it.
What is
the difference between TRUNC and DELETE in SQL commands?
TRUNC
faster
dependent tables cannot work
DELETE
slow
row-by-row
cannot applicable for large tables
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