David Abramowicz

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since Dec 10, 2004
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Recent posts by David Abramowicz


It seems that the new curriculum for SCEA (310-052):

Has a number of changes in comparison to its predecessor.

Has anyone analysed the specific changes?

Here are a couple of things I've noticed:
- No UML
- Web Services
- Explain how you would design a Java EE application to repeatedly measure critical non-functional requirements and outline a standard process with specific strategies to refactor that application to improve on the results of the measurements.

Thanks /Dave
- Does the J2EE spec dictate that the http session object must be available on all servers in a cluster?

- If not, why not?

Thanks /Dave
The errata can be found here:�


and is basically a list of known errors and typos in HFJS

Cheers /Dave
Thanks everyone.

I have decided to go for the current SCBCD... EJB 2.0/2.1 is what everyone uses nowadays and I can't be asked waiting till April to start with the next cert...

Hmmmmm.. I've come to realise that get certifications is addictive

Cheers /Dave
Hey All.

Passed the SCWCD last week. Got 94%... Test was easy. You know the way HFSJ and Enthuware try to catch you out by including obscure details and little traps... Well the real exam doesn't do that.

I read SCWCD twice... Once properly and second time just skimmed it making notes.

I then read through my notes once and took all Enthuware exams once. The exams are value for money, though I must say... The end of chapter exams in HFSJ are closer to what you'll see in the exam in terms of focus.

I got around 78% average on Enthuware and 71% in the final exam of HFSJ. DO TAKE the final exam in HFSJ, it really helps you when you read through the answers etc...

Recommendation for HFSJ readers, keep the errata close at hand... Other than that I reckon it's a really good book.

Now that I polished off SCJP, SCJD and SCWCD.... I wanna do SCBCD, but right now it is SOOOOO outdated... Question is, when will the exam be updated?... and when will HFEJB be updated??

GL everyone.

Do a search on your problem in this forum...

Basically I'm guessing your using IE, which has like a "use friendly error pages" setting. If that switch is flicked, you wont see the custom error page.

Cheers /Dave

Originally posted by peter wooster:
One question, did you wait and notifyAll on the Map or on an individual record?

Hi Peter!

For synchronisation of the lock and unlock methods I actually used the Data class, even though in hinesight it might have made more sense to lock on the Lock Map.

However, for the addRecord method I used a different object for synchronization. The add record method has jurisdicition over deleted and to-be-created records and the lock and unlock methods have jurisdiction over the others... Since there is no interdependency I think it made sense to separate the synchronization to increase concurrency.

Cheers /Dave

19 years ago
Congratulations !
19 years ago
Hi everyone.

First of all thanks for supporting me in getting this assignments done. I would have got a much worse score if it wasn't for you!

I had the B&S assignment.

I downloaded the assignment in August last year and worked full time on it three weeks. After that I basically didn't touch it till Christmas, when I found javaranch and after browsing the forum re-engineered the GUI about three times from my original monolithic lump I guess I spent about 5-6 * 40 hours on the assigment. But I believe the time could have been reduced to about half had I read the articles in this forum first, created a complete design and THEN developed (I just took a RUP course ) rather than my more explorative programming approach.

This is the outline of what I implemented:

- Used a traditional client server model. Got a LOT of really useful information on this forum to back my decision.
- Performed server-side locking
- Used RMI
- Stored timestamped locks in a hashtable
- A timer task removed expired locks at a configurable interval
- The timestamps remove the recognised deadlock possibility
- Used notifyAll()
- No lock on read operations
- Used a Vector to cache records
- Data file only read on startup
- Had an (excessively?) dynamic GUI, which could absorb changes to schema etc along with abstract baseclasses for MVC etc... Went a little overboard here.
- Used JTextField for searching
- No unbook button

I am fairly certain that the lost points for general considerations are for the fact that I ignored mentioning anything about the Ascii reading of the file, and more importantly that I did not discuss the choice to use AbstractTreeModel. This is mainly because that particular stuff I did in August last year and I'd forgotten all about it

Don't really know what's next, it's a toss up between IBM's RUP Consultant and SCWCD. My boss reckons the former but I'm more interested in the latter...

Good luck to everyone who's still doing the assignment!


[ April 12, 2005: Message edited by: David Abramowicz ]
[ April 12, 2005: Message edited by: David Abramowicz ]
19 years ago
Hey all, after waiting 6 (!) weeks for my results and hassling prometric grade the darn assignment I have finally got word that I passed.

These are the results:

This report shows the total number of points awarded for each section. 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 83
Documentation: 70 70
OOD: 30 30
GUI: 40 40
Locking: 80 80
Data Store: 40 40
Network Server: 40 40
Total: 400 383

What I have next-to-no professional experience with is GUI development... So most of my development time was spent re-engineering the GUI Every time I read a new description of the MVC design pattern I seemed to re-program the entire user interface! I still have not found a really good MVC tutorial, most of them are to trivial or too abstract, or too JSP-Servlet-POJO orientated.

... The rest was easy.

I will give a more detailed description of what I did when I get home from work.

Cheers /Dave
19 years ago

Having a JComboBox would involve one of these three poor options (in my humble opinion) :

- loading all possible search values at app start-up and never refreshing them

- loading all possible values every time a user clicks a search field

- having a complex caching mechanism that is somewhere in between the two options above

The third option I could live with, but it seems much too complex for this assignment.

Instead I just went with the simple approach of the JTextField, but with a little checkbox that can remove the exact nature of the search (to make the application somewhat usable

However, I have known people to pass using both JTextField and JComboBox so I guess it's what you can live with.

Cheers /Dave
Congrats Peter.

I don't know if I interpreted you correctly, but I have a colleague who used notifyAll() and got 80/80 for locking.

Cheers /Dave
[ March 24, 2005: Message edited by: David Abramowicz ]
How do you know the record hasn't been deleted while you were waiting?


I believe you will have something like "only one application will have access to the data file at a time" in your instructions.html. I found this to be rather contrary to the "you may not change the data schema as other applications utilise the data file", however I guess these applications only have read-access.... An interesting thought is also that if other applications have write access to the data file, it completely invalidates the locking

Anywho.... Since you have exclusive write access to the data file, as long as you update your data cache when you perform writes, you can be sure that the cache sports accurate data.