balaji sambandam

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Recent posts by balaji sambandam

You can read the following books and may serve as a
reference guide while you are doing the assignment.
Core Java volume 1 and Volume 2
Graphics JAVA Mastering JFC.
Java 2 Exam Guide - Barry Boone/william Stanek
You don't need to read the whole book. Read only chapters
which are needed to compelete assingment such as
RMI
Swing classes
sockets
I/O
LayoutManager
and etc...

And don't forget to read RMI tutorials and archives at
SUN site (if you plan to use RMI in your assingment)

Originally posted by Balaji Sadasivam:
Congratulations Balaji!!
Can you tell me the objectives of this exam?? The objective given in the Sun web-site is not clear. I need some specific topics.
Also can you recommend some study materials??
Is it necessary to study books related to "Object-Oriented Analysis and Design" ??
Please do reply.
Thanks
Regards
Balaji


Send a mail to Sun and ask their permission for a resubmission.
Thistime, before you send the jar file, try unpacking them and see if it has all the files you wanted to send.

Originally posted by Michael Chang:
Thanks for your response. My submission is a jar file as a whole as Sun required. In the jar file, there are two folders: docs and starting. Under the docs folder, all javadoc files are there following their package structure. And there is source.jar that has all source code for my assignment. If you extract source.jar, you will get the source code in proper directory structure. Under starting, there are four jar files that contain the class files and the policy files that you should deploy to client and server machines respectively. I clearly stated in my README.txt that my source code is in source.jar under the docs directory. I don't know what I did wrong. Any idea?
Thank you very much.


Hi,
You can find a very useful and descriptive explanation about the
assingment in developer section of "Java 2 Certification - Jamie Jaworski " book.

Originally posted by shivani anand:
Balaji,
First of all I should congratulate you for such a great acheivement.
Could you please write details about the asssignment given for Developer certification. This will help me to decide whether to take this exam or not.
Thanks in advance
Shivani


The sun code conventions clearly mentions it should be
int myMethod () {
//code
}
So I wouldn't take any risks of losing some marks for a silly
thing. Even I had the same thing in mind when I started
my assingment and got used to it.

Originally posted by Matt DeLacey:
I just took peek at Java's Coding Conventions based on someone's post recently. One thing that struck me: they should you should do your braces as such
int myMethod () {
//code
}
That just drives me crazy! I prefer the good old:
int myMethod ()
{
//code
}
The rest of the rules I use or can live with changing them. How strictly do you think you have to adhere to that standard? I mean, I don't want to loose points, but it's also almost impossible for me to make myself write code the other way. It is much harder for me to read. What are your thoughts? I know it seems pretty trivial, but I'm going to download the assignment in 2 weeks and I'm getting nervous and wanting to get all my ducks in a row.
With Respect,
Matt DeLacey


Read the developer sample questions at sun site and
revise your desing choices you made in your assingment
and you are good to go!

Originally posted by tony lu:
I have almost finished the assignment, and I wonder what is the question for the coming essay. Is there anybody who has experience on passing the essay? if possible , give me some hits.
thank you in advance.


Could you list all the contents and directory strcture
of the submission.jar file and I will be able tell you where it could have gone wrong

Originally posted by Michael Chang:
Can someone please help me to figure out what I did wrong? I can't pass the exam without knowing what I did wrong. I posted the following question several days ago but got no direct answer.
Thanks a lot!


1. The server-side database with network server functionality
This is the server program which handles all the database
coming from the clients (through data client program).
3. A client-side database program that handles the networking on behalf of the user interface.
This is the Data client program/class which is used by the
clients to do all the database operations.
Basically you will have to provide all the public methods
,you defined in the server program, in the DATACLIENT program as well.
DATACLIENT will be in the client side (i.e in the machine
where GUI is running). If GUI needs to any database operation
it will call DATACLIENT method and dataclient will in turn
call server methods.
The basic idea of having DATACLIENT is that it acts as
proxy server in the client side and if there are future changes in the server methods , we can tweak dataclient program
a bit so that GUI need not be altered.
Remember DATACLIENT acts as abridege for generic GUI programs
that need to perform database opertaions on the FLIGHT server database


Originally posted by Ramesh Kadur:
Hi,
In the instruction, under Overall Architecture, it says that the application has 3 key parts:
1. The server-side database with network server functionality
2. The client-side graphical user interface
3. A client-side database that handles the networking on behalf of the user interface.
The second part is clear. Can any body (Balaji Sambandam ??) explain what 1 and 3 are and difference between them? Is the instruction telling me that I have to have two databases - one on the client side and another on the server side? If we have two databases then they should be identical and the application should assure the synchronization of the databases. Having two databases does not make sense to me.
Is this a 3 tier application? I can only see two tiers - Client side GUI and Data Server. If the database, flat file in our case, is itself considered as another layer then it becomes three tier.
Your explanations are appreciated.

Thank you.
Ramesh Kadur


You need to write a new method called criteriafind

Originally posted by lucy hu:
hi, guys,
the instruction of my assignment says I need to implement three methods: criteriaFind(String), lock(int) and unlock(int), I found the latter two methods in Data.java source code, but couldn't find the criteriaFind(String) method, is there something wrong?
Regards
Lucy


you need to have db package in both client and server
side

Originally posted by John McWon:
I could not understand "The DB package should be accessible in both client and server side". You mean one the server side need the DB package or both server and client side need the DB package? I think both will need because you need the DB package in client side so that you can declare DataInfo and fieldInfo instances at the client side. after the declaration, you can assign values which passed from the server side, right?


The DB package should be accessible in both client and
server side as the server returns DataInfo and fieldInfo
object during database operations

Originally posted by Da Zhu:
As we know the methods in Data class may throw DatabaseException, I am wondering if your guys pass this exception to the client side, say to the gui class.
If yes, then the DatabaseException.class has to be
on the client side too, while I think we should move all
the db package to the server side.


I didn't change the format as it's not a requirement in
the spec.

Originally posted by Da Zhu:
Hi Balaji,
Thanks for your explaination. Although it looks strange that the lock method throws IOException, since all other public methods catch IOException and then throw DatabaseException, I will stick with the given signature. No reason to take the risk of modifying signatures.
One more question, did you format your data, say change the input data 11h65m to 12h5m? If yes, at which stage do you make such formating (during data conversion, in retrieving data from database, or in JTable column formating)? I know 11h65m looks silly, but I do not see anywhere in the instruction that asks for data formating.


Hi qi,
If there is an invalid record reference (i.e if
a client tries to lock record with record number
0 or less than -1 (-1 is DB lock) ) or if the user tries
to lock a record No that is not in the
database then I will throw an IO exception
Hope this helps

Originally posted by Da Zhu:
Hi Balaji,
A question on the lock method:
public void lock(int record) throws IOException
Does your code possibly throw IOException? How?
Regards,
Da Zhu


[This message has been edited by balaji sambandam (edited January 02, 2001).]
[This message has been edited by balaji sambandam (edited January 02, 2001).]
Hi,
I know it's not a fool proof method. I didn't want to mess around with lock and unlock methods's parameter (as sun
prefers a simple solution to a compound one as suggested in the guidance document). I just wanted to implement both methods without any change in the signatures.
If every client follows this rule in order
1) lock
2) book the ticket
3) and unlock
there wouldn't be any problem. When a record is locked by the first client , it cannot be locked by another client. The next client will have to wait till the lock is released by the first guy. We have to make sure in the GUI that a client does n't call unlock method randomly. When a user confirms the booking, every client will have to first call lock method , book the ticket if necessary and finally call unlock method.
Hope this helps.

Originally posted by Qi Chen:
Hi Balaji,
Thanks for your response.
I understand your opinion and I agree with you that the specs can be implemented in different ways, but do you really think your approach implemented the requirements I quoted?
More specifically, notice the word "by this connection" in (1), and the word "the caller" in (2).
I guess in your approach, a record locked by one caller of the method lock(int) can be unlocked by another caller of the method unlock(int).



[This message has been edited by balaji sambandam (edited January 02, 2001).]
Hi guys,
You can read the following books and may serve as a
reference guide while you are doing the assignment.
Core Java volume 1 and Volume 2
Graphics JAVA Mastering JFC.
You don't need to read the whole book. Read only chapters
which are needed to compelete assingment such as
RMI
Swing classes
sockets
I/O
LayoutManager
and etc...
I read relevent sections from the follwing certification books just for reference.
Java 2 Certification - Jamie Jaworski
Java 2 Exam Guide - Barry Boone/william Stanek
And don't forget to read RMI tutorials and archives at
SUN site (if you plan to use RMI in your assingment)
This is just my opinion and that's what I did to compelete
assginement.
Balaji
Hi,
All we need to know( inside the lock method) is whether a record
has been locked and We don't need to know who locked a record.
Each record has a record number (See the DataInfo class)
and we need to have some mechanism to keep track of the
list of record that are locked in lock method.
If a client calls unlock method with a record no(which is not
locked by any client), we don't need to take any action.
Anyway this is just my view. It couldn't have been implemented
in many different ways.
Hope this helps.
Balaji

Originally posted by Qi Chen:
Congrats, Balaji.
Since you said for locking you did not use any client id, I
am wondering how you achieved the following:
(1) from instruction:
If an attempt is made to unlock a record that has not been locked by this connection, then no action is be taken.
(2) from code comment of the unlock method:
Ignore if the caller does not have a current lock on the request record.
Thanks.