Stoian Azarov

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Recent posts by Stoian Azarov

I am also interested in some materials for this certification exam. I plan to go to the training next month so I want to prepare in advance.
If anybody have some information about the exam I would be thankful for any suggestion and guideline from where to start learning.
Hi Paul,
I also was puzzled by this answer option and made some test. In fact you are not getting any compilation error, deployment error nor exception at runtime. The only problem is that the server sends back empty response with code 200 OK. So the user has no clue what is going on.

I checked again Servlet 3.0 Specification and API and here are some quotes that are ALMOST saying that you are supposed to do either chain.doFilter or fill out the response:


6.2.1 Filter Lifecycle
The doFilter method of a filter will typically be implemented following this or
some subset of the following pattern:
1. The method examines the request’s headers.
4. The filter may invoke the next entity in the filter chain. The next entity may be
another filter, or if the filter making the invocation is the last filter configured in the
deployment descriptor for this chain, the next entity is the target Web resource. The
invocation of the next entity is effected by calling the doFilter method on the
FilterChain object, and passing in the request and response with which it was
called or passing in wrapped versions it may have created.
The filter chain’s implementation of the doFilter method, provided by the
container, must locate the next entity in the filter chain and invoke its doFilter
method, passing in the appropriate request and response objects.
Alternatively, the filter chain can block the request by not making the call to invoke
the next entity, leaving the filter responsible for filling out the response object.


API doFilter method

A typical implementation of this method would follow the following pattern:
1. Examine the request
2. Optionally wrap the request object with a custom implementation to filter content or headers for input filtering
3. Optionally wrap the response object with a custom implementation to filter content or headers for output filtering
- Either invoke the next entity in the chain using the FilterChain object (chain.doFilter()),
- or not pass on the request/response pair to the next entity in the filter chain to block the request processing
5. Directly set headers on the response after invocation of the next entity in the filter chain.

Hi Adolfo,
Can you provide the EL expression that throws javax.el.ELException. I have been trying to simulate your example but without any success. My error page is working even if I define it in DD with java.lang.ArithmeticException.

There is no book for the new version. All the available resources are here
I have seen many duplicate reports, so I suppose that there is not established process of editing the existing posts.
Even though we might ask o'reilly for any case.
Then it is good to correct the errata because someone reported the same mistake(wrong correction).

And this proposition even got approved
Errata - Page 843 Question 30
Just some more info directly from specification:
Servlet 3.0 Specification, 13.8.1 Combining Constraints

The combination of authorization constraints that name roles or that imply roles via
the name “*” shall yield the union of the role names in the individual constraints as
permitted roles. A security constraint that does not contain an authorization
constraint shall combine with authorization constraints that name or imply roles to
allow unauthenticated access. The special case of an authorization constraint that
names no roles shall combine with any other constraints to override their affects and
cause access to be precluded.

Some of the uses are:
- asynchronous EJB method invocation
- chat
- RESTful web services
- quality of service

- improves scalability
- not blocking container threads
12 years ago

10) Are there any drag and drop questions on the 1z0 - 858 exam?

I think that the answer is NO. I can't say from my experience but since the exam is offered by Pearson VUE I think that drag & drop questions were removed from this exam.
@Bear Bibeault - sorry for intervening, I do support the idea that the best way to learn is by thinking and searching for explanation by. I will be more careful the next time.

@mohitkumar gupta - the info you provide is a little sparse. what does that mean:

I get nothing in the output corresponding to this EL

- there is no output
- the whole EL expression is printed(plain text)
- nothing strange in the console

Just a fast thought - the first element of you EL expression should be either implicit object or scope attribute.


if developer is set properly in one of the 4 scopes, of course.
I plan to sit the exam next week. I wish this book had already been published!
Thanks for the response Ghita, I appreciate the information.