Wednesday 31 October 2012

WAS INTERVIEW PART-3 QUESTIONS AND ANSWERS


      WAS INTERVIEW PART-3 QUESTIONS AND ANSWERS

1)  What is the default admin console port number in websphere?

A)  WebSphere Application Server default ports

 •Web container port (HTTP_TRANSPORT) - 9080
•Web container secure port (HTTPS_TRANSPORT) -  9443
•Administrative console port (HTTP_TRANSPORT_ADMIN) -  9090
•Adminstrative console secure port (HTTPS_TRANSPORT_ADMIN) -  9043
•Name service or RMI connector port (BOOTSTRAP_ADDRESS) -  2809
•Simple Object Access Protocol (SOAP) port (SOAP_CONNECTOR_ADDRESS) -  8880
•Data replication service client port (DRS_CLIENT_ADDRESS) -  7873
•Java Message Service (JMS) queued port (JMSSERVER_QUEUED_ADDRESS) -  5558
•JMS security port (JMSSERVER_SECURITY_PORT) -  5557
•JMS direct port (JMSSERVER_DIRECT_ADDRESS) -  5559
•Secure Association Services (SAS) SSL server authentication port (SAS_SSL_SERVERAUTH_LISTENER_ADDRESS) -  9501
•Common Secure Interoperability Version 2 (CSIV2) server transport port (CSIV2_SSL_SERVERAUTH_LISTENER_ADDRESS) -  9503
•CSIV2 client transport port (CSIV2_SSL_MUTUALAUTH_LISTENER_ADDRESS) -  9502



    WebSphere Deployment deployment manager default ports

 •Administrative console port (HTTP_TRANSPORT_ADMIN) - 9090
•Adminstrative console secure port (HTTPS_TRANSPORT_ADMIN) - 9043
•Name service or RMI connector port (BOOTSTRAP_ADDRESS) - 9809
•Simple Object Access Protocol (SOAP) port (SOAP_CONNECTOR_ADDRESS) - 8879
•Data replication service client port (DRS_CLIENT_ADDRESS) - 7989
•Cell discover port (CELL_DISCOVERY_ADDRESS) - 7277
•Secure Association Services (SAS) SSL server authentication port (SAS_SSL_SERVERAUTH_LISTENER_ADDRESS) - 9401
•Common Secure Interoperability Version 2 (CSIV2) transport port (CSIV2_SSL_SERVERAUTH_LISTENER_ADDRESS) - 9402
•CSIV2 transport port (CSIV2_SSL_MUTUALAUTH_LISTENER_ADDRESS) - 9403
•Object Request Broker (ORB) listener port (ORB_LISTENER_ADDRESS) - 9100


  WebSphere Application Server node agent default ports

•Name service or RMI connector port (BOOTSTRAP_ADDRESS) - 2809
•Simple Object Access Protocol (SOAP) port (SOAP_CONNECTOR_ADDRESS) - 8878
•Data replication service client port (DRS_CLIENT_ADDRESS) - 7888
•Secure Association Services (SAS) SSL server authentication port (SAS_SSL_SERVERAUTH_LISTENER_ADDRESS) - 9901
•Common Secure Interoperability Version 2 (CSIV2) transport port (CSIV2_SSL_SERVERAUTH_LISTENER_ADDRESS) - 9101
•CSIV2 transport port (CSIV2_SSL_MUTUALAUTH_LISTENER_ADDRESS) - 9201
•Object Request Broker (ORB) listener port (ORB_LISTENER_ADDRESS) - 9900
•Node discovery port (NODE_DISCOVERY_ADDRESS) - 7272
•Node multicast discovery port (NODE_MULTICAST_DISCOVERY_ADDRESS) - 5000


WebSphere Application Server JMS server default ports

•Java Message Service (JMS) queued port (JMSSERVER_QUEUED_ADDRESS) - 5558
•JMS security port (JMSSERVER_SECURITY_PORT) - 5557
•JMS direct port (JMSSERVER_DIRECT_ADDRESS) - 5559
•Simple Object Access Protocol (SOAP) port (SOAP_CONNECTOR_ADDRESS) - 8876



2)  Is it possible to a server to listen to multiple port numbers in WebSphere? Explain

A) ---->  yes.. There is a possibility to listen the multiple port numbers in Websphere.This is possible when we deployed the two applications on the single server.

---->  We must add the ports of that particular servers in virtual host.

---->  Environments---> virtual hosts---> default_host---->host aliases---> new --->add that ports in the virtual host.




3) What are the responsibilities of Web container, EJB container and JNDI?

A) ---->  The webserver plug-in examines the url, verifies the list of host name aliases from which it will accept traffic based on the virtual host information, and chooses a server to handle the request.

  WEB CONTAINER :

----->  A stream is created. A stream is a connection to the web container.The web container receives the request and based on the url, dispatches it to the proper servlet.

----> If the servlet class is not loaded, dynamic class loader loads the servlet. 


JNDI : (JAVA NAMING AND DIRECTORY INTERFACE) 

----> JNDI is used to look up of either databases or ejb connection by the servlet. JNDI directs the servlet depending on the servlet request.

----> To the corresponding database and gets a connection from its connection pool in the case of servlet wants the datasource

----> To the corresponding EJB container, which then instantiates the EJB when EJB is requested.

----> IF ejb container have to execute some sql operation , it has to go to the jndi to lookup the datasource.

----> The sql statement is executed and the retrieved data is sent back to the EJB or to the servlet.

----> Data beans are created and handed off to jsps in the case of EJBs

-----> The jsp generates the html, i e sent back to through the plug-in to the webserver

-----> The webserver sends the output page to the requested browser



4)  What happens to applications if node agent is not running?

A) ----> When DMGR goes Down then there is no impact to the end-users. If NA is goes Down then there is no problem in Distributed Environment/Clustered the servers will server the application when we maintaining fail over mechanism. (NA is nothing but communication between Dmgr and federated nodes). 

-----> Before starting the app server the applications NA must be up and running then only it serves the applications which are running on that app server.

----> If the application is deployed on multiple servers, the remaining  servers will serve the application request.



5) In WebSphere 6.0 and 6.1, If you got a problem before creating a log's directory, at that time where will you the check status of installation?

A) ----> After installing the websphere product. you can see the status of the installation either it is success or failure. 

----> you can see this status in WAS product home--->logs------> install------> see the log.txt
----> If your installation is not success. i e your product is not created... u can see the status of the installation in windows user account waslogs. you can see the status there 



6)  What is the difference between Vertical and Horizontal clustering? What is the use of Horizontal and Vertical clusters? Which performance better among these two?

A) ----> Clustering is mainly to provide Fail-over capability. i.e if one server is goes down automatically the other server which is having the same configuration i.e replica of failed server have to serve the application request. This is achieved through the clustering.

---->  In realtime we use the horizontal clustering. i e building the replica of servers on different nodes. it provides the fail over capability.


----> In Vertical clustering, we will build the replica of servers on one node which fails to provide the Fail over capability.

7) What happens if a profile is federated to DMGR at that time when it is stopped? What happens to the applications under the Servers in WebSphere 6.0 ?

A) ---->  There is no impact on running of applications on the servers when the DMGR is in running or  in stopped state. 

----> DMGR is just only for admin purpose only. NO applications are running on DMGR

8) what is the difference between system out.log file and trace.log file ?

A) ----> systemout.log and trace.log are almost the same but trace has more description about the JVM rather in other words we can say that trace has more information for troubleshooting the issue .

---->  keep in mind that enable trace only when required and later disable as it will fill up the filesystem and it will effect other application if unnoticed.

9) what are FFDC logs ? what is the use of that ?

A)  ----> FFDC is first failure data capture it is a log which the IBM asks when there is a PMR opened with them .

----> you can also analyse the ffdc log through log analyser.

10) If we get page cannot be displayed then how you are going to troubleshoot the issue ?

A)  ---->  It is a HTTP 404 error. If you get this error we need to check the logs for application Server status. The page expecting by the request is not finding that means request is reaching the server but it is not available at expected location.

---> logs means for application errors or status of your application we have to seen JVM logs (SystemOut.log,Systemerr.log)

----> First try to hit the web server if that is good then hit the application server directly if both of them work then there is an issue with plugin.sometimes the web server will be in hung state kill the web server processes which can be found 

---->  command ps -ef |grep . kill all the process and restart the web server.

----> Now try the above steps again and also check the status of the app server (JVM)



11) What are the different templates available to create a profile ?

A)  WAS V7 profile templates
----> cell
----> Default
----> Managed
----> dmgr
----> management
----> secureproxy


12)  What is the use of Service Integration Bus ?

A)  ---->  WAS 6.0, has a new feature called "Service Integration Bus" i.e. a new pure-Java JMS engine. 

----> SIB is a complete JMS v1.1 provider implementation. 

----> A bus is a group of one or more interconnected servers or server 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.

----> The following capabilities are provided by a service integration bus: 

1. Application sharing message with other system.
2. A message-producing application
3. A message-consuming application


---->  A service integration bus supports asynchronous messaging; that is, sending messages asynchronously. 

----> Asynchronous messaging is possible regardless of whether the consuming application is running or not, or if the destination is available or not. 

----> Point-to-point and publish/subscribe messaging are also supported



13)  How do you check heap is used by JVM ?

A)  ----> You can use third party monitoring tools like Wily Introscope or ITCAM and also there is inbuild monitoring tool in admin console called TPV ( Tivoli Performance Viewer) under Monitoring and Tuning.


14)  How will you verify the version of WAS in WebSphere?

A)  ----> go to directory bin directory of web sphere install root
/opt/IBM/WebSphere/App Server/bin
and run the command 

./versionInfo.sh

You can get the version of web sphere application server installed.



14) What are the differences between web sphere 4.0,5.0 and 6.0.

A) ----->  Web Sphere Studio 3.5, comes up with Visual Age for Java.

     -----> WSAD 5.0 supports J2EE 1.3 java specifications. 

    ------> RAD 6.0 (RATIONAL APPLICATION DEVELOPER) supports J2EE 1.4 and integrated with Eclipse 3.0, UML Visual Editor, Tomcat Jakarta, Ant scripting, EJB universal test client and SOA tools.


15)  In IBM WSAD, server crashes sometime while running in debug mode .Is there any way to prevent it ?

A)  ----->  you need to increase the memory allocated to java process in WAS. In WASD deployment description there is a setting for java process memory allocation. Increase the Xml values in it and see 

                              (OR)

-----> You need to bump the heap size memory default is 0,0 Enable administrative console in the wsad in the server settings I believe its configuration tab or environment . And log on to the admin console on port 9060 when u start the server in normal mode HTTP://localhost:9060/admin. Then go to server/ server1/process definition/JVM Increase the initial heap and maximum heap size in there.. Give atleast (512MB,1.5Gb) And restart the server in debug mode. Its should work.



16)  When using the WebSphere, Which three updates would force you to restart the test environment?

A)  ---->  These are the situation when you need to restart the server in test mode.
      -----> 1) When you make any changes to the Class file(Bean , DAO etc)
      -----> 2) Change any properties that were declared in properties file related to the whole application.
     ------> This is because initially properties file that were declared for the application will be loaded only when  the server starts, and the server picks up thos key, values
     ------> 3) No need to restart if you make any change for jsp file. But you need to comeout of that particular page or refresh the page , so that it will recompile the modified jsp file and generate new contents
 
      -----> But you need to restart the server when you change the servlet file.
    ------> 4) If the database connection between the DB server and APpserver fails. Because
the connection pool and all will be declared in the properties file.




17)  If the app server crashes in the middle of application deployment , what could be the reason and what steps we have to follow?

A)  ----->   If the server resources are less while deployment, when application requests are hitting application server due to less resources the application server will crash. 

------> If the application server crash then that time we can get thread dump.


18)  What is the default port for SSH server?

A)   22


19) What is Process Definition  ?

A) ----> Process Definition specifies run-time characteristics of Application Server process.

     -----> It includes Characteristics such as JVM settings , standard in , error and ouput paths and User ID and Password under which a Server runs.


20) Tell me the flow of a request from client to the server and server to the client ?

A)  Browser->HTTP Server(s)->HTTP Server->App Server Domain (Web and EJB container)--->DB...and vice versa


21)  What is singleton? What is the purpose of singleton? How to get connection in websphere portal server?

A)  Singleton class is a class in which only one instance of the object exist at any point of time. So a Singleton class is basically used when we want to restrict instantiation of a class to only one object. "Application" class, print spooler, database connection are examples of a singleton class. In a singleton class the constructor is made private and a private static is declared that reference of same class. A static variable is used for instantiating the class. Singleton class are not cloneable.


22)   what is managed server ?

A)  After federating a node from Application Server profile to Manager Profile, the node becomes Managed Node, so the servers which are running under that particular node automatically becomes managed servers (previously those are unmanaged servers, because they belongs to unmanaged node i.e; before federation) this is nothing but managed server.

----->  The server which is running under a node which has a node agent is called as Managed Server


23)   Explain architecture of WAS ?

A)   WebSphere architecture consists of one or more computer systems which are called nodes. Nodes are available within WebSphere cell. A WebSphere cell can have one node. On this node all the needed software's installed. If a WebSphere cell contains more than one node, then all the software components are distributed among the nodes. The software components that are installed in one node can share in the distributed environment. This distribution enables for scalability, reliability. 


The following are the components

1)   A web server which provides the services of HTTP 

2)  A database server for data persistence

3)  WebSphere Application Server (WAS)




24)  WAS EDGE COMPONENTS  ?

A)  Caching Proxy
      Proxy Server
     Load Balancer
     Network Dispatcher Component
     Content Based Routing (CBR)
     Site Selector Component



25)   what is the difference between L1, L2, L3?

A)  l1- is basic level (monitoring, basic configuration)
     
     l2 -back up who are senior staff (trouble shooting)
     
     l3 –architechts (designing / architect/ requirement(ram/box))


26)   What is the difference between WAS and WL?

A)   1. In weblogic u cant do clustering accros the domain,but in Websphere u can.
      
      2. In weblogic all the configurations are stored in a single file called Config.xml ,but in Websphere its stored in a directory structure called CELL
     
      3. In weblogic u can start the managed server without a Adminserver(using MSI-config.xml),in websphere u can not start a node with out Dmgr.
      
     4. In websphere u can add webserver as a unmanaged node where as u cannnt do that in weblogic.


27)   How do enable GC? (GARBAGE COLLECTOR)

A)  In the Administrative Console, expand Servers and then click on Application Servers.

     ----->   Click on the server that is encountering the¬ "OutOfMemory" condition.
     
    ----->  On the Configuration tab, under Server¬ Infrastructure, expand Java and Process
Management, and click Process Definition.
    
    ----->   Under the Additional Properties section, click Java Virtual¬ Machine.
    
    ----->   Select the Verbose garbage collection check box.
    
    -----> Click Apply
    
    ----->  At the top of the Administrative Client, click Save to apply changes¬ to the master
configuration.
   
    ----->  Stop and restart the Application Server

  ----->  The verbose garbage collection output is written to either native_stderr.log or
native_stdout.log for the Application Server

 ----->  verbosegc – Tells you what is being done, whether heap size is at min or max.

3 comments:

Unknown said...

amaging

Unknown said...

excellent stuff.thx a lot

Frozen said...

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