Samrat Roy

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Recent posts by Samrat Roy

pablo santamarta esteban wrote:First of all, congrats!

I really like this thread as i was looking for something like this, talking about how is the hole process! I'm thinking about starting studying the certification, but i'm not sure if i'm ready to take it!

What i'm still wondering is if you need to code anything in the assignment part. Is it necessary? Or you have just to think and send how the solution is going to be and that's all?
s
Thanks in advance.



No Coding required , just design diagrams are all that is required for 1z0-865 . 1z0-807 is objective and 1z0-866 is essay.

Yago Segura wrote:Congratulations !!! I'm just starting the road you did . This threads are really helpfull



Thanks Yago , May the odds be in your favour
My Story on completing 1Z0-807 , 1Z0-865 and 1Z0-866

Yesterday I got the email from Oracle that my results were available for the final round of exams (1Z0-865 and 1z0-866) and with trembling hands I opened the link , but was delighted to see that I passed the last exam with a score of 155/160 (~ 97%).

In the next few paragraphs I will illustrate my journey and provide pointers to fellow enthusiasts on the preparation for OCM – the highest certification one can get from Oracle.

1Z0-807 Oracle Certified Master, Java EE 6 Enterprise Architect – Scored 83%:
I started preparing for the certification around mid-2016 and finally wrote the 807 exam in December 2016 , in these six months , I explored most of the Java Landscape which covered all JEE topics like , servlets , JSP , EJB (Very Important) , JMS , ORM, Transactions , JEE Security and others .

For any one starting on this phase I strongly recommend the following resources .


1. Buy OCM JavaEE 6 Enterprise Architect Exam Guide by Bambara and Allen .  This book is indispensable for this certification. It will provide a structure for your studies as you will be able to break down your effort into discernable areas.  Fair Warning – The chapter exercises and CD accompanying this book are utter rubbish and adds little value. The content of the book itself isn’t too much in depth either. The purpose of this book is to get you started on the path of exploring JEE features and keep you on track for the certification at hand.  Having said that , by the time you appear for 1Z0-807  , make sure that you are thorough with this book and can recall everything written in the book.

2. Refer to the freely available JEE Official tutorial available at this link  https://docs.oracle.com/javaee/6/tutorial/doc/ . This will provide the in depth view of the JEE technology the book is missing . Reading and understanding this entire tutorial is the main course of preparing for the exam . Do not Skimp on this .  The approach of using this tutorial is to first read a chapter from the book , find a relevant chapter from the JEE6 tutorial and read it in depth . During this time it is also helpful to make small POC’s as when required so that you understand what is being said.

3. Whizlabs practice tests .  Do this on the last month of the prep . I wrote my 807 in December 2016 so I started practicing tests in the October – Nov Timeframe. Do Not do this early in the preparation as you run the risk of memorizing answers which is counterproductive.  I evaluated both whizlabs and EzPractice labs for this exam ,  I had bought both practice tests . My side by side evaluation is that EzPractice labs has too many repeated questions in the tests and the explanation for the answers aren’t clear and many time the provided answers are plain wrong. In contrast  Whizlabs is much better . I recommend Whizlabs . EzPractice labs isn’t worth the money spent.
4. Read the stories on code ranch and google as many concpets as you can . Websites like DZone are good on the technical articles on JEE6.
As far as the exam itself is concerned, the questions asked in the exams are not going to be straight forward questions and the level of difficulty is much  greater than what is asked in the practice tests , give a thorough read of the exam questions , most questions are going to be open ended and I felt that at places multiple answers are correct but you have to choose one . In those cases , pick the one which fits the best after playing the Devil’s advocate for all the given solutions .  You will have sufficient time to finish the exam . Time is not a concern here.


1Z0-865 / 866 Oracle Certified Master, Master Assignment and Master Essay – Scored 155/160 (~97%)

1Z0-865  Oracle Certified Master, Master Assignment
This exam is a different ball game all together. Here the objective is not to create a working solution but to design and account for all the aspects of the given problem.
Before you start this exam , take classes on UML . I took the training on OOAD and UML from Oracle as training on demand as training is mandatory for getting certified . Also read Martin Fowler – UML distilled.
Second thing to do before registering for 865 , is to find a UML tool which you find comfortable in working with . I used Sparks Enterprise Architect as it is concise provides all of required pallets, Star Uml is also an option .

I took 5 months to make my assignment, I was slow in making the assignment but I was thorough, I could not spend my weekdays on this so I spent at least 6 hours per Weekend on this, every weekend for five months .

When you get the download of the problem after registering for 865,  don’t start the design immediately .  For the first week just sit with the problem , I tried to find as many open questions as possible in the problem statement as the problem statement is very open ended and omits a lot of information for which you are expected to make assumptions.  For the first two weeks , live the problem and doodle it with a pencil .
You second goal should be identifying design problems and try to match GOF and JEE design patterns to solve the problem .  Writing code for this isn’t required and should be avoided for the most part . However if you choose to use Enterprise architect , you can quickly design the problem Domain model in java pojos and import the src directory in EA to generate the class diagram . For rest of the design , stay away from coding.

Another problem most novices (including me at the time) face is , which diagram to start working on first ? The problem statement usually asks for Class , Sequence , Component and finally  deployment diagrams.
I followed the following sequence .
1. Write down the list of assumptions you are taking while designing on a piece of paper.

2. Class Diagram – work on this first . Add all the necessary design patterns and add sufficient notes in the diagram . Make this diagram as easy to read as possible . Class diagrams tend to get cluttered very quickly  , so spread out the diagram . You should add all necessary objects including placeholders for JSP/ JSF page and such .   After the first draft of class diagram ; jump to sequence diagram immediately , donot try to make class diagram perfect in the first go , you will inevitably revise it when you make the sequence diagram.

3. Start Sequence Diagram – This is grunt work if your class diagram is well thought. Use sufficient optional fragments and if a sequence is getting too big ,break it and use reference fragments.  In my case , writing sequence diagrams revealed a lot of flaws in my original class  diagram so I went and altered the class diagram .  At the end of this exercise , your CD and SD should be in good shape.

4. Start Component Diagram – This is the easiest diagram , if you can devote 8 hours , your diagram will be ready in one day.  The only problem I faced here is that the definition of a component is very loosely defined in the industry , even the diagram elements like port and delegation connectors are very loosely defined. I used the definitions and examples provided in uml-diagrams.org to base my diagrams upon and they worked fine.

5. Start Deployment diagram – While the diagram is easy, I struggled with providing a capacity planning for this diagram , so I spoke with a few industry gurus to see the standards and case studies they had . I modelled accordingly .


After this all you need to do is package it and upload.

1Z0-866 Oracle Certified Master, Master Essay

If you have done your work for 865 then this will not be difficult . It is a two hour exam and you usually get 8 questions .  Before the exam , get into the habit of writing , in the exam they usually ask how you handled various nonfunctional requirements like availability , reliability security etc etc . They also ask about your technology choices, and a few What-IF  scenarios .

The best preparation for this exam is to use a simple text editor lie notepad or notepad++ and write the points you considered for each NFR . Then you refine each points progressively . The last chapter of the book OCM JavaEE 6 Enterprise Architect Exam Guide by Bambara and Allen helps a lot here .
Once your points are made ,  challenge yourself to express those points as multiple essays in two hours , around 250 to 300 words per essay . Do this exercise in notepad or notepad ++ as the exam tool only has a text box without word count or dictionary, however the exam tool does provide copy paste features.

Having a good tying speed is crucial for the exam , as time will be short and you will not get an opportunity to think for an extended time.
If you cannot write an essay or long text, writing bulleted points also works , I chose this route for some questions in this exam.

That’s it !


Hi All,

What is the best resource namely Book / Tutorial to learn jbpm 4.4 ?

The book Jbpm Developer guide by Mauricio "Salaboy" Salatino is a very old book and only covers upto jbpm 3.2 .

jBPM 3.2 is vastly different from jBPM4.4 and I dont see a newer edition covering 4.4 !

Please suggest a beginner friendly book for JBPM 4.4 !!

Regards
Samrat
7 years ago
The application I am currently working throws up ugly stack traces if the url entered is wrong ; For example :

if you enter http://blahBlah.zapdata.com the tomcat will display an UGLY HTTP status 500 with a Catalina stack trace :


This is not a valid address.. But if you enter http://blahBlah.google.com , the website displays a clean error message like .


How can I configure tomcat to display clean error messages and not a stack trace?

I have tried the error page tag <error-page><error-code> in the web.xml of the application , that works fine if there is a genuine problem with the application but not when the initial url entered is wrong.

Please HELP !!!
8 years ago
after doing dome searching , it is really starting to look like an OS restriction. The Virtual address space available per process , the way windows [A 32 bit Windows OS] allows is 2^32 meaning 4GB.

out of this 4GB , 2GB is allocated as the user space and the rest is the kernel space which can not be used to do use full work by the process.



If you look at the logs posted above, Physical memory is available , virtual memory is available what is not available is the Virtual address space! my guess is, the native C process swells up to maximum permissible level from the OS and yet demands more , this is where the OS intervenes and stops the memory allocation.

This results in an out of memory error , which is sent to the java layer .

References :
1.Thanks for the memory : IBM article.

2.Virtual address space , Microsoft Support
8 years ago
Hi All!

The application I am currently hooked to is using Native C code to do all the searching and sorting and returns the result back to the java Code.

When a large job is submitted , the application generally has had it (The damn thing crashes!!).

the issue was traced to the Native Code , and it is appearing to be running out of virtual address space when a large job submitted, the available physical ram, virtual memory all seem to be ok :

The log file from inside the C code.
Failed to allocate handle of 131072 bytes for file <C:\zapOtherSrc\cpp\dev\mods\util1\STRMCACH\strmcach.cxx> at line 99.

Heap Manager statistics
]r*** 1 MEMORY ALLOCATIONS FAILED!
Currently allocated: 1,106,050 handles, 999,874k
Total allocated: 40,389,251 handles, 45,530,388k
Total freed: 39,283,201 handles
Total won't see free: 0 handles
Total realloced: 2,487,794 handles
Maximum amount allocated: 999,874k from file <C:\zapOtherSrc\cpp\dev\mods\base\STR\str.cxx> at line 1328.
Largest allocation: 27,321k from file <C:\zapOtherSrc\cpp\dev\prods\zap\engine\misc\lsconverter.cpp> at line 328.
(These numbers do not include MFC, CObject-derived and specialty allocs.)
(The Currently and Max amount allocated also do not include our 'new' allocs.)
System memory in use: 54%
Physical memory size: 2,047m, free: 1,861m
Page file size: 4,095m, available: 4,095m

Virtual address space size: 2,047m, available: 9m

End Heap Manager statistics

Exception message: Out of memory.
Exception thrown from file <C:\zapOtherSrc\cpp\dev\mods\base\HM\hm.cxx> at line 390



Now is there is a way to increase the memory allocated to the C code ? Till the point I have searched , the -Xmx and -Xms options only allocate memory for the java Heap, and the Native heap is separate , so increasing the java heap size wont do anything.

Is there a way to start up the JVM so that it allocates more memory for the Native code? or are we looking at the 32 bit restriction presented by the OS?


Thanks in advance!
8 years ago