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Jeff X Williams

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since Sep 28, 2001
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Recent posts by Jeff X Williams

Wow, that's the best score I have heard of! I can't believe they lowered the passing score to 58%. Maybe they should concentrate on making their questions better instead of lowering the bar.
These are poorly written questions because they give conflicting requirements and wrong answers. The real exam is not quite this bad. If the question states that performance and/or memory are a big concern then the answer is almost certainly going to be SAX.
The author of the question (I guess) would say that performance and memory are secondary to the other requirement, but I would say that if you don't have enough memory to load the document using DOM, then nothing else matters. You CAN sort using SAX (might be hard, but possible) and you CAN search for a few elements using SAX (may actually be more efficient than DOM anyway), but if you don't have enough memory to load the document using DOM then you CAN'T sort and you CAN'T search for a few items.
So, the bottom line is the answers given to these sample questions are WRONG! There really aren't any good sample exams that don't contain bad questions like these and are similar to the IBM style of questions. The closest is the IBM sample XML exam.
If your preparation time is limited, you need to focus on 3 things:
(1) XML Schema
(2) XSLT
(3) DTD
Slightly lower priority, but still important are:
(4) DOM
(5) SAX
(6) XPath
Everything else has high-level or brief coverage on the exam.
My score on the IBM practice test was about the same, 82% I think. I didn't think I had done that well on that on either. There's something about the way IBM writes questions that makes them seem more difficult than other exams.
I have also passed SCJP and SCWCD exams and some Microsoft exams and they all had a fairly large number of what I would call simple questions, where you can be certain you got the correct answer. IBM offers very few of these easy ones, so it shakes your confidence.
My recommended approach would be to study the sources I listed above very thoroughly. However, the exam still manages to find areas that are not covered by those books. But my strategy is to study a few sources very well rather than many sources lightly. That way you should have a deep enough understanding to sense the correct answer even when they throw in something obscure.
Finally, don't spend too long on any one question, because time is a big factor. Since there are 57 questions and 90 minutes, when you have one hour left, you should at least be on question 19 or 20. With 30 minutes left you better be on question 40 or so. If you fall behind from this pace it will be very difficult to catch up and you may start to become careless as you rush to beat the clock.
Good luck. Be sure to let us all know how you do on the exam.
It was my first attempt. I studied for about 4 months about 1-2 hours per day. Even with all that preparation I didn't feel confident in a lot of my answers because many of the questions are worded in a confusing way. But, just go with the answer(s) that seem most reasonable and you should be OK. In other words, the questions are hard, but they don't seem to be "trick" questions.
Also, be sure to take the IBM practice XML test because it is fairly close to the style of questions on the real exam. Although, the real exam is slightly harder.
I actually thought I might have failed the exam, so I was very surprized to see that my score was 84%. That should tell you something about the difficulty of the questions. They are so poorly written that you can never be sure that
you got a question correct even if it is on a topic you studied thoroughly. But, luckily the most reasonable guess seems to usually be the correct answer. The test really doesn't go very deep into technical questions, but when it does,
it always manages to throw in an aspect of the topic that you wouldn't think was important enough to study carefully.
What makes this test so difficult is that almost every question asks for the 2 or 3 "most correct" answers and there are hardly any questions that are really straightforward, so it is very hard to tell how you are doing. Also, time is a big factor. I could not spend as much time on questions as I wanted to and finished with only 2 minutes left. I had marked 14 questions for review, but only had time to quickly look back at 3 of them. So, when the message popped up on the screen saying "Congratulations, You Passed!" I was both surprized and elated.
Here's how I prepared:
Professional XML 2nd Edition - Chapters 2-6, 8-12, 24, 27
XML Schemas - Chapters 1-9
XSLT - Chapters 1-8
The XSLT book is not necessary, in my opinion. The coverage of XSLT in PXML2 is very good and almost as deep as this book. The XML Schemas book is very good and was essential for me because I thought the coverage of XML Schemas in the PXML2 book was very poor.
I also did just about all the mock exams I could find, but none of them were even remotely similar to the style of questions on the real exam. However, they do help a little to get your mind into the mode of analyzing questions.
(Please do not waste your money on the WhizLabs exam. Not only are the questions way easy; it consists of a lot of true/false questions and there is not one true/false question on the real exam.)
So, the bottom line is that you have to study both broadly and deeply to have a chance at this exam. And then, it almost seems more like a reading comprehension test than a test of your XML knowledge. Although I think the exam is terribly written, I learned a lot about XML from my studies and am very happy with my passing score.
According to Pro XML 2, SAX is twice as fast as DOM, and uses 1/10 the memory so I still think the answer given for this question is wrong.
Thanks for the very clear explanation. That makes perfect sense.
In XPath, is there any difference between the count() and last() functions? If you had a nodeset of 3 elements they would both return the value 3, correct? It's just that count() returns the number of nodes and last() returns the position of the last node. But, wouldn't these always be the same, or is there something more subtle that I am missing?
I was able to install it fine, but I was surprized by how poorly done this sample test is. I would recommend that you not waste your time on it. It won't help you prepare at all.
I disagree. SAX can't give you random access, but you can still search for a particular element. If this question was meant to imply a requirement for random access, it failed to. I can only hope the real test is written much better than this. I'll find out tomorrow when I take the exam.
Does XSLT load the entire document into memory before it begins processing? I read in ProXML2 that you could pre-process a document with XSLT before processing with DOM if memory is a concern. But, this doesn't make sense to me if XSLT also has to fully load the document before processing it. How would this save memory?
Thanks. Where is a space needed, after the comma? I hope the real test doesn't focus on such minor details as a missing space.
The following question is from the DOM/SAX sample exam on this site. It gives the answer as (b), but there is no way that can be right. Everything I have read says SAX is to be used when memory and performance are a concern. Am I misreading the question, or does this sample exam just suck?
4. There is XML data document which is very large. The application is to extract the very few of its information from document. The memory & speed may be a constraint. Which is the most likely method to be implemented?
a) Extract the information using SAX API, event based methods.
b) To extract the information using DOM API.
c) To extract the necessary information and process using XSLT.
d) To use schema based approach.