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J2EE Scenarios

 
Samson Annamdevula
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Hi Folks
After skimming through all the messages posted, I am suprised that I didnt find anyone sharing their "J2EE scenario" questions they came across in the exam.
Those of you who cleared the exam, if you could please paraphrase the questions (obviously) and post them, I think forum is a great place to dicuss how different scenarios can be approached.
If its aganist the rules then ignore and stop throwing stones at me.
Thanks for ur time
Samson
 
SJ Adnams
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They are of this form...
A Client-Server scenario is given, with features of the firewall, features of the client, features of the server(s).
You are asked what needs to be done to get things working.
e.g you have 2 servers behind the firewall with different ip addresses obviously. The web server serves up a java applet which tries to make a connection too server 2,- it can't because of security so you need to redirect (maybe over an SSL port) then the webserver does forwarding.
I might put a few on my mock exam ;)
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http://www.x-nt.com
 
SJ Adnams
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I have added some questions to my mock exam.
They are question 39, 40, 41 and 42.
(www.x-nt.com/questions.html)
Please don't ask me what the 'correct' answers are, I just made them up. But you should be able to answer a case for and against & figure it out for yourself.

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http://www.x-nt.com
 
Samson Annamdevula
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Hi
Thanks simon for taking some time to come up with some questions, I really appreciate ur effort.
Guys, please let me know if I am wrong with my answers
Question 39
A company currently has a webserver and an application currently accessed via vt100 terminals on a second unix machine. Both machines are behind the company firewall which allows HTTP and HTTPS traffic.
The company wishes to make the application available over the internet for use by external clients.
(select the best solution)
1) Rewrite the application to use CGI, basing the cliet on html forms.
2) Use a commercial vt100 java applet client, use HTTP tunnelling on the webserver to redirect 443 to port 23 on the second unix machine.
3) Use a commerical screen-scraper application on the webserver to access the second machine.
4) Rewrite the application using EJB, JSP and Servlets.

Answer : 2
let me go one by one
1 is wrong bcos a JAVA solution is the best
4 is wrong bcos it is a 2 tier approach and EJB is redundant
3 could be right but not the best approach as 2
Question 40
You have successfully implemented a J2EE solution for a client. The client has become concerned that it's databases may be vunerable to malicious attack (hacking) what do you suggest as a solution.
(select the best solution)
1) Tell him you have tested the code and can see no way in which access can be compromised.
2) Suggest creating a DMZ for the Web and Application Servers.
3) Suggest creating a DBZ for the Web Server.
4) Suggest a secure solution is possible by switching to SSL and issuing X500 certificates to each client.
Answer : 2
1, 3 obviously out of question, initially thought 4 was the best, but 2 is the best bcos the purpose of DMZ is toprevent hacking by keeping the legacy systems / databases unexposed to the internet.
Question 41
A Car Exhaust company is currently using leased lines to each of it's 300 nationwide depots with a 3270 client at each depot. The company urgently needs more than 1 terminal at each depot.
(select the best solution)
1) Start collecting requirements for a J2EE Solution
2) Switch to VPN to solve immediate problem
3) Implement a screen scraper based application
Answer : 2
I could be wrong, just a best solution from my perspective
Question 42
Your J2EE solution that you implemented has been a huge success. The number of customers is almost 5 times what has been anticipated and performance is becoming an issue
(select the best two)
1) Add more RAM to the 4 processor 4GB RAM Appserver
2) Add another AppServer set the webconnector to round-robin
3) Add a second network (LAN) card to the web server
4) Upgrade the database hardware
Answers: 1, 2
Thanks for ur time guys
-S-
 
SJ Adnams
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The last one I meant you to choose the database upgrade. AFAIK adding more RAM when you have 4GB isn't going to do any good (limit is 512M for jvm?)
They are more for the style of question than right/wrong.
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Shankar Ranganathan
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Hi Samson
You are right for all the questions and we should take Simons info for the last answer
Thanks
Shankar Ranganath
 
Naichen Liu
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Simon, how do you know the memory size limit for JVM is 512M? we can use -Xms and -Xmx to set up memory limit for JVM, and if we don't specify, we will have a default initial size but not uplimit size. Could you please clarify?
For Q42, if we can increase RAM as long as # of cpu, it could be a valid answer, because JVM uses thread extensively, and no matter how many threads we configed for container or how many beans/objects in container, they still need to switch among CPUs,
so only increase memory size won't work.
 
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