Walter Vetrivel

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Recent posts by Walter Vetrivel

technically u can do it, I did it, but disadvantage maybe is that
architect exam involves less or no coding at all.
Walter
Thanks Raghav.
19 years ago
Hi Everyone,
I have been following all the posts on this site and hope that I will get some advise on my next step.
I passed my B.E in electrical and electronics from madras India in 1992 and ever since have been working in the electrical industry, primarily the construction side of it, sometime in august'2000 i.e last year the software bug bit me since I heard of all my friends and classmates from college going to the US and other places earning in dollars.......etc.
I decided to enter the software industry since working as an electrical engineer in Dubai was not as lucrative as some of the new IT jobs a few of my classmates were doing in the US.
I realised I had 2 options either "networking" or "software development".
And ofcourse that time JAVA was hot! so I bought a few books on JAVA and sat down to study after 2/3 months of striving hard I finally passed the SCJP in December'2000, after which I travelled to India fom Dubai on vacation, there I was lucky(or I thought so!!)to find someone who promised a job in UK with a consultant provided I learnt EJB,XML etc and also he said he would provide me with experience for a few months in India befor he sent me to UK, which was fair and looked good too.
After spending my vacation, a major portion of which I spent learning the basics of EJB, JSP etc , I returned to Dubai in feb 2001 and decided to prepare for the SCEA-PART 1 exam. After slogging for 3 months I managed to clear the exam in May 2001. I immediately contacted the person in India who had promised me a job in UK, he said and is still saying that the job market in the Uk is still bad. Going by the events shown on CNN the job market is going to be slack for another 6 months or more so I am not trying to go anywhere and have not opened a book or written any code since past few weeks.
I do not know what to do now, any ideas???
Thanks
Walter
19 years ago
pretty soon, about 2 months for scjp, 3 for scea.
All the best.
Hi Mark
I dont see any projects here, Thanks in advance
Walter.
19 years ago
thanks guys and yes its a big relief.
Walter.
more specifically u should be looking for DNS round robin info , u can find it on amit jnagals page.
Walter
Thanks to all of you good people out there, and by god's grace I passed
Continuing in the tradition I would also like to post my perspective on the exam,
No of questions(approx)
concepts }
common architectures } 5
legacy connectivity 4/5
EJB }
Ejb container model } 13/15
protocols5
applicability of j2ee10
design patterns5
Messaging4
Internationalization2
Security4
There are atleast ten really long questions which are time consuming to answer and yes,those dragons with 7 heads(options).
I dont know what protocol runs on 10001.
Uml exhibits 5 nos.
and a lot of questions with exhibits too.
A lot of common architecture knowledge like the notes posted by John particularly clustering should help.
In Uml mulplicity indicators, messages in sequence diagrams.
Design patterns proxy, iterator etc.
In legacy VT100 terminals and screen scraping.
In internationalization, java.text and I/o , refer john's notes too.
Security refer to java tutorials and applet faq etc.
Ejb just know the life bean instance life cycles and transactions.
Though the j2ee blueprints help in getting a picture on the applicability part of j2ee a lot of questions were tough.
Firewalls and applets ofcourse.
JDBC resultsets.
Be prepared to read a lot and quickly too.
I had a tough time with the exhibits and the questions, having to scroll up and down , there is a tile option too.
The exam is timed well(enough time) and people who have taken the scjp will not have a problem.
Thats all for now, all the best to all of you.
Walter Vetrivel.
I meant security context identity.
Anyway I think u are right.
At what point, precisely, in the life-cycle is a stateful session bean considered created?
before ejbcreate method and after setsessioncontext method, since identity is available in the ejbcreate method.
At what point, precisely, in the life-cycle is a stateless session bean considered created?
after the ejbcreate method since the bean gains identity at this point.

Please correct me if Iam wrong.
Mr.Wetherbie's notes

Common Architectures
Scalability
Scalability is the ability to economically support the required quality of service as the load increases.
Two types: Vertical and Horizontal
Vertical:
Achieved by adding capacity (memory, CPUs, etc.) to existing servers.
Requires few to no changes to the architecture of a system.
Increases: Capacity, Manageability
Decreases: Reliability, Availability (single failure is more likely to lead to system failure)
Vertical scalability is usually cheaper than horizontal scalability.
J2EE supports vertical scaling because of automatic lifecycle management. Adding more capacity to a server allows it to manage more components (EJBs, etc.).
Horizontal:
Achieved by adding servers to the system.
Increases the complexity of the system architecture.
Increases: Reliability, Availability, Capacity, Performance (depends on load balancing), Flexibility
Decreases: Manageability (more elements in the physical architecture)
J2EE supports horiz. scaling because the container and server handle clustering and load-balancing.
Availability and reliability are obtained through scalability.
Scalability affects capacity. The more scalable the system is the more capacity it can support. This must be traded-off against the complexity & manageability costs.
Maintainability
How related is this to Flexibility?
Flexibility is the ability to change the architecture to meet new requirements in a cost-efficient manner.
A flexible system should be more maintainable in the face of changes to the environment and/or to the application itself.
Flexibility improves: Availability, Reliability, Scalability
Flexibility slightly decreases: Performance, Manageability
Flexibility is achieved via code that can be distributed across servers with load balancing that prevents one system from being overburdened. The use of a multi-tier architecture also helps achieve flexibility.
Reliability
The ability to ensure the integrity and consistency of the application and all of its transactions.
You increase reliability through the use of horizontal scalability, i.e., by adding more servers. This only works up to a certain point, though.
When you increase reliability you increase availability.
Availability
Availability is about assuring that services are available to the required number of users for the required proportion of time.

Extensibility
The ability to modify or add functionality without impacting the existing functionality.
The key to an extensible design is to make an effective OO design. Extensibility pays the most towards the font end of a system.
Some rough guidelines:
More than 25 top-level classes will lead to problems
Every use case should be able to be implemented using domain model methods
J2EE supports extensibility because it is component-based and allows you to separate the roles of an app. JSPs can handle presentation. Servlets can handle routing, and EJBs can handle business logic.
Performance
Architectural performance is concerned with creating an architecture that forces end-to-end performance.
The purpose of an architecture that ensures performance is to control expensive calls and to identify bottlenecks.
If you know the boundaries of the various parts of the system, the technologies, and the capabilities of the technologies you can do a good job of controlling performance.
You want to minimize the number of network calls your distributed app makes - make a few "large" calls that get a lot of data vs. lots of calls that get small amounts of data.
Try to minimize process-to-process calls because they are expensive.
Use resource pooling to reduce the number of expensive resources that need to be created like network connections, database connections, etc.

Manageability
Manageability refers to the ability to manage a system to ensure the health of the system.
A single tier or monolithic app would be more manageable from a management perspective than a multi-tier system but this must be weighed against the possibility of a change rippling through a monolithic app.
A simple architecture may not be as flexible or available as a more complex system but the amount of effort required to keep the system up & functioning will be less.
A component-based architecture like J2EE offsets some of the manageability problems caused by a multi-tier system.
Security
Security ensures that info is neither modified nor disclosed except in accordance with the security policy.
Tradeoffs: personal privacy, ease of use, and expense.
A highly secure system is:
More costly
Harder to define and develop
Requires more watchdog activities
Principles of Security:
Identity - The user is correctly ID'd thru an authentication mechanism
Authority - The user can perform only allowed activities
Integrity - Data can only be modified in allowed ways
Privacy - Data is disclosed to authorized entities in authorized ways
Auditability - The system maintains logs of actions taken for later analysis

The Question and answer for question 10 does not seem right.
Classes loaded into a browser from the local network are trusted.
This can be considered false since only classes from the same jvm will be trusted and not from a different jvm in the local network.
Classes loaded into a browser from remote sources are trusted if they are signed.
classes can be signed only if they are in a jar file, so this is false.
Classes loaded into a browser from remote sources are trusted if they are in a signed jarfile.
classes can be given extra privileges if signed but still cannot be trusted fully, hence this can be considered false.

Classes loaded from a jarfile on a remote source can sometimes be trusted even if the jarfile is unsigned.
This looks like the most improbable answer, and I don't understand how it is right.
Classes loaded from a signed jarfile are trusted if the public key associated with the jarfile's signature is marked as trusted in the keystore.
This ans does not make sense so its false.

Please clarify.
Thanks Walter