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Gustavo Dutra

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since Jan 26, 2005
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Recent posts by Gustavo Dutra

Hi Titus,

The lock is the real problem of the application,

I implemented the lock in two phases,

this happens because of the lock method, this

EVIL method only receive two arguments, the identification

of the client was not informed.... SO...... the only form

to make this work is to set an attribute value, but the attribute

is not thread safe, so you have to synchronize the first part

(the lock set) and then lock again (the lock object) to implement the

wait/notify protocol.... with this implementation you make the acquire lock

thread safe....

I did not receive 100% in the lock problem....

I think they want a lock manager or I made a mistache.... I don�t know...

well....

It doesn�t matter...

now is only celebration

I hope it helps you,

Gook luck


Gustavo
15 years ago
I would like to thank everybody that make this

group so rich with a lot of steps and tips to

make the right decision in the project.

Yesterday I received my results and I have to thank the

group,

good luck for every body.

My result was:
The maximum number of points is 400, to pass you need a score of 320. Section Summary:
Section Max Actual Points Points
General Con: 100 100
Documentation: 70 70
OOD: 30 30
GUI: 40 40
Locking: 80 65
Data Store: 40 40
Network Server: 40 20
Total: 400 365

Gustavo Dutra Martins
15 years ago
Thanks,

How is the real exam different from Mock Exams. Are the really Exam
questions very tough compared to Mock exams.


My test had 30% of questions like the mocks, simple and objective questions, this part was easy, some mock questions are more difficult than
this type of questions on the exam.
25% was in the middle, jms, ejb, patterns , architecture ....
but... the rest.... was difficult, subjective questions, where the question had 2/3 lines and each option 2 lines, you have to read a lot and think a lot, this part is totally different from the mock, but the mocks help giving you the key parts to study.


How many questions you had on EJB. How many on Patterns.



--> EJB - 5 or 6 - you have to know the specification, it is very, very mor easier than the SCBCD exam.
--> Patterns.... I think 5 or 6 too.

Which topics are more complicated.


for me ....
legacy and the Big one's .... with a lot of information, crossing concepts
like J2EE, security and legacy.

Good Luck,

Gustavo
Hi friends,

I would like to thank the job that everybody do in this forum.

It is a big reposity of knowledge and helps me a lot.

The test is different from the mocks... but.... the mocks help a lot

to understand the problems used on the test.

The test is difficult,

and my advice is to study hard and pray a lot... .

I study the 2 books for the certification and Ramu Meda material,

every chapter I read I try to find more details on the books and on the

internet (google is a very nice partner... )

My links ...

Common Architectures:
- http://www.javaworld.com/javaworld/jw-10-2000/jw-1027-pool.html
- http://java.sun.com/j2ee/sdk_1.2.1/techdocs/guides/j2ee-overview/Introduction.fm.html
- http://www.javaworld.com/javaworld/jw-02-2001/jw-0223-extremescale.html
- http://www.onjava.com/pub/a/onjava/2001/09/26/load.html

Internationalization
- http://java.sun.com/docs/books/tutorial/i18n/intro/index.html

Messaging
- http://java.sun.com/products/jms/tutorial/1_3_1-fcs/doc/copyright.html

Patterns
- http://www.dofactory.com/Patterns/Patterns.aspx#list
- http://www.tml.hut.fi/~pnr/Tik-76.278/gof/html/
- http://www.jguru.com/faq/view.jsp?EID=10636
- http://www.jguru.com/faq/view.jsp?EID=37813

Protocols
- http://www.good-stuff.co.uk/useful/portfull.php
- http://www.csis.gvsu.edu/~adams/Teaching/Notes/Networking/http.html
- http://www.blackmagic.com/people/gabe/iiop.html

RMI
- http://java.sun.com/products/jdk/rmi/reference/docs/index.html
- http://java.sun.com/products/jdk/rmi/reference/docs/index.html
- http://java.sun.com/developer/onlineTraining/rmi/exercises/DistributedGarbageCollector/
- http://java.sun.com/developer/onlineTraining/rmi/RMI.html#RMIArchitectureLayers

Security
- http://www.securingjava.com/
- http://java.sun.com/docs/books/tutorial/security1.2/overview/index.html
- http://java.sun.com/docs/books/tutorial/security1.2/TOC.html#tour1

Modelling
- http://www.agilemodeling.com/style/
- http://www.informit.com/articles/article.asp?p=336264&seqNum=1&rl=1
- http://www-106.ibm.com/developerworks/rational/library/3101.html

Geral
- http://leocrawford.org.uk/work/jcea/part1/internationalisation.html
- http://prasks.webahn.com/scja.html
- http://www.harishramchandani.com/

Thats all.... i hope it helps....


Well... my scores...

Concepts................ 100%
Common Architectures ... 83%
Legacy Connectivity..... 40%
EJB..................... 100%
EJB Container Model .... 75%
Protocols............... 100%
Applicability of J2EE... 66%
Design Patterns ........ 80%
Messaging............... 100%
Internalization ........ 100%
Security ............... 100%
I agree,

look at this site:

http://www.precisejava.com/javaperf/j2ee/EJB.htm#EJB140

but the exam cover EJB 1.1 .... so...

I think Lim is correct.
Hi,

only Entity Beans can be reentrant.

It is in the specification, session and MDB cannot be reentrant.
Hi Friends,

one more question about javacoding mock exam.....


QUESTION :
What considerations make sense when writing an entity bean?

a) Use BMP when storing standard datatypes and performance is essential (CORRECT) ???

b) Use BMP when storing standard datatypes and performance is not essential

c) Use BMP when storing complex datatypes and performance is essential (ANSWERED) (CORRECT)

d) Use BMP when storing complex datatypes and performance is not essential (ANSWERED) (CORRECT)

SOLUTION:
BMP can easily be used to store complex datatypes (in contrast to CMP), it's performance depends partially on the bean programmer's work



Well, every article that I read on internet said CMP improve performance using cache and another features implemented by the container.
The articles said programmers have to be dba's to create betters queries than the container...

I agree with the problems about complex types, but performance .....

Any idea....
Hi,

I am doing the javacoding mock exam, and I missed the following question:


Which technologies are security-related?

a) JAAS (ANSWERED) (CORRECT)
b) WSDL (ANSWERED) (WRONG) ???
c) JCE (ANSWERED) (CORRECT)
d) JSP
e) JSSE (CORRECT)



the b answer - WSDL - are security related???

I went to W3C web site but I did not find anything about security....

Thanks,

Gustavo
Well James,

I think we will discover the answer together...


What kind of architecture should we take as the reference, when we talk about the J2EE application architecture? traditional client/server system, or 2-tier J2ee application model?



I think n-tier(5 is a good number )
is the appropriate reference, 3-tier is the minimum, you
can break the middle tier (presentation,business and integration).

There is an article that enumerate the tiers:
1.web-client
2.presentation
3.business
4.integration
5.resource


Scalability

If the middle tier is separate (3-tier approach) you can make a cluster of computers to increase, you can make a cluster on the web or application server.

Availability
Availability is the same about scalabity, but it depends a lot on the configuration of the balance to work properly


Security
You have security on the web container and on the ejb container, either declarative and progrmmatic...

Manageability

cade says on his book:

Manageability is the ability to manage the system to ensure the continued health of a system with respect to scalability, reliability, availability, performance, and security. Manageability deals with system monitoring of the QoS requirements and the ability to change the system configuration to improve the QoS dynamically without changing the system. Your architecture must have the ability to monitor the system and allow for dynamic system configuration.



I think manageability is true.... it is transparent for your "Business Logic", "Presentation Logic" and "Controller" if there is a cluster or if there is a replication, this is a container responsability .

Let start a discussion....

[ ]s

Gustavo
Hi all,

Can someone tell me where can I find

information about Design Patterns(GoF) specifically to EJB specification.

I mean correlate the patterns(GoF) that the EJB specification uses,

for example:

The EJBHome correlates with what factory pattern?

Services (transaction, security, log) provide by the EJBObject ??

Thanks,

Gustavo
Dear Friends,

page 82 of the specification....

" The Bean Provider cannot assume that the Container will always invoke the ejbRemove() method on a session bean instance. The following scenarios result in ejbRemove() not being called on an instance:
- A crash of the EJB Container.
- A system exception thrown from the instance�s method to the Container.
- A timeout of client inactivity while the instance is in the passive state. The timeout is specified by the Deployer in an EJB Container implementation specific way. "

The specification do not mention anything about the passivate state...
I agree that you spend resources... but.... if you have some logic or verification or desalocation of resources???
The ejbPassivate callback method have to close connections, do things for
the session bean that will be stored.... not removed....

This is my opinion....

Read the page and take your conclusion..

Bye,
Gustavo
Dear,

I am trying the final exam of the HF book,

The question 46 has the following affirmation:

" Setter methods for fields associated with a primary key MUST NOT be
exposed through a client view ",

the book says it is true,

but on the specification, page 130 we have the following paragraph:

"Once the primary key for an entity bean has been set, the Bean Provider must not attempt to change it by use of set accessor methods on the primary key cmp-fields. The Bean Provider SHOULD therefore not expose the set accessor methods for the primary key cmp-fields in the component interface of the entity bean. "

LOOK, the word is SHOULD instead of must.....

I know that a IllegalStateException must be thrown if the bean provider try to modify the key value, but I did not find anything about the restriction
used on the question.

Any idea???

Thanks,

Gustavo
Linda,

EJB 2.0 specification is your bible for this test.... :-)


http://java.sun.com/j2ee/1.3/docs/index.html

download the EJB 2.0 specification.

if you want more specif details about the test,

go to

http://www.sun.com/training/catalog/courses/CX-310-090.xml

they list the exam objetives.

Good luck....