Victor Bucutea

Guys, do you have any ideas/suggestions?


Thanks,
Victor

Just a small correction,

# Did you represent the Local interface (of the EJB) in the class diagram?

It can be good because this way you have interfaces to show in your component diagram, but the class diagram is already becoming so bloated, I don't know how the examiner will cope with all the nice squares and lines...

If you can give me just some pointers...

Thanks,
Victor

Hi everybody,


I've working for some time on the SCEA part II and I was wondering how you guys solved some aspects:

Did you represent the Local interface in the class diagram?

One of the sequence diagrams is getting extreeeemly large. It's becoming rather annoying to read. I'm sure this has happened to your design before and I'm wondering whether you have split it in multiple diagrams.

How did you represent for ex. a <<proprietary API>>. I've just provided an adapter interface, and represented it as a Stereotyped class... But I'm not sure about it. Should it be present only in the component diagram or only in the class diagram ?

Thanks
Victor

hey guys...

Sorry for insisting, but I'm really stuck on the points below, so if you happen to know/suggest how I could solve just some of them please reply...


Victor

Hey,

I'm currently creating my diagrams and I hope you guys can give me some pointers. Perhaps you can give examples of how you solved these problems

Application connects to an external system which 'uses JMS to communicate'. How do I model/represent this system in the sequence diagram, and in the class diagram?

How should I represent a WS call which is made from my application in the sequence and class diagram? I followed a tutorial which represents the WS client as a 'component' in the class diagram and sequence diagram. Do you know whether this is a good/bad idea?

Do you know any ways to handle exceptions in the sequence diagram ?

How detailed does the class diagram need to be? I mean all classes present in your application ( like utilities, frameworks, logging ) should be represented in the class diagram?

Luay Abdulraheem wrote:I finally bought the assignment from (https://ibt1.prometric.com/oracle) simply because ... I couldn't find any other place to download it from
Best wishes for ALL !

I want to download the assignment too, but sadly the url above does not work for me.

As per the FAQ, I've mailed [email protected] on this matter, and I'll keep you updated on the replies....

Ranganathan Kaliyur Mannar wrote:hmm...In the other post by Rishi, they have replied saying that you have to 'upload' through person. and I am unable to schedule for essay as it wouldn't even list the exam.

Right I have somewhat the same problem. I'm trying to take part I of the exam, but I can't find the exam 1Z0-864 (SCJEA part I ) in my pearson vue account. I can only find the SAMPLE-864.


so are we supposed to wait until 31st of may, and after that the exams will be listed in the pearson vue account?


Vignesh says that you can only access the Part 3 of the exam after mid June. Is this the case also for SCEA Part 1? Has anybody taken part 1 since oracle migrated to pearson vue?


Thanks,
Victor

Hi ,


regarding the tomcat service of JBoss I have some questions.

The server.xml of the tomcat service is this :


<Service name="jboss.web.usermanagement"> <Connector port="8090" address="${jboss.bind.address}" maxThreads="10" maxHttpHeaderSize="8192" emptySessionPath="true" protocol="HTTP/1.1" enableLookups="false" redirectPort="8443" acceptCount="100" connectionTimeout="20000" disableUploadTimeout="true" /> <Engine name="jboss.web.usermanagement" defaultHost="localhost" jvmRoute="ppo-v000100-ld-node1"> <Host name="localhost" autoDeploy="false" deployOnStartup="false" deployXML="false" configClass="org.jboss.web.tomcat.security.config.JBossContextConfig"> <Context path="/userManagement" docBase="" /> </Host> </Engine> </Service>

This would create a service for port 8090. The thing is that this service responds to every request on port 8090 not only (/userManagement), and when passing the url http://localhost:8090/userManagement , as the Context path attribute states, it simply shows me a directory listing of the runtime folder. The path attribute should point to the root of the web application, but being on JBoss, the root of the web application is deployed inside an ear file, so it would be a mess if I were to hard code the name of the ear file.

First question is, how do I specify the docBase without specifying in the path attribute the name of the ear file which contains the ear?

Second questions is a bit more complicated. I need to make ONLY context path '/A' respond on port 8090 and all other context paths should be normally accessible on port 8080 ?

Thanks,
Victor

Has anyone found a solution to this problem?

I'm trying to achieve pretty much the same thing, without using virtuat hosts.

Hi guys,


Thanks for all the big help you've provided. Keep up the good work.

General Considerations (maximum = 100): 90
Documentation (maximum = 70): 69
O-O Design (maximum = 30): 30
GUI (maximum = 40): 31
Locking (maximum = 80): 80
Data store (maximum = 40): 40
Network server (maximum = 40): 40


It seems I overdecorated the GUI. Other than that I can't say what were the things that lowered my score.
Nevertheless I'm very satisfied with the result.

Thanks again,
Victor

Hi Khaled,


SOAP attachements are not enabled by default. If you were do deploy a service like this :
@WebService() public class PictureManager { @WebMethod(operationName = "retrievePicture") public Image retrievePicture( @WebParam(name = "inImageNumber") final int inImageNumber) { } }

the Image object would be returned to the client, depending on the SOAP style ( document or rpc ), as an BASE64 encoding right into the XML .



this would be the HTTP response headers :
Transfer-Encoding=[chunked], Date=[Sat, 06 Feb 2010 10:17:14 GMT], Content-Type=[text/xml;charset="utf-8"] . .



and this would be the SOAP response:

<?xml version="1.0" ?>
<S:Envelope xmlns:S="http://schemas.xmlsoap.org/soap/envelope/">
<S:Body>
<ns2:retrievePictureResponse xmlns:ns2="http://service.ivan.com/">
<return xmlns="">iVBORwEWDx...</return>
</ns2:retrievePictureResponse>
</S:Body>
</S:Envelope>

However, if you would use the @MTOM annotation when deploying, like this:
@WebService() @MTOM(enabled = true, threshold = 128) public class PictureManager { . .

Take note that MTOM is used as an optimization of transferring large amounts of data through soap.
The server would optimize binary transfers through SOAP, that is use the attachment part of the SOAP message to encode the Image:

HTTP response headers:

Transfer-Encoding=[chunked], Date=[Sat, 06 Feb 2010 10:30:03 GMT], Content-Type=[multipart/related;start="<rootpart*05a5f89a-1dbb-4abc-9bf6-897e896c8dbc@example.jaxws.sun.com>";type="application/xop+xml";boundary="uuid:05a5f89a-1dbb-4abc-9bf6-897e896c8dbc";start-info="text/xml"]


And this would be the WSDL generated by the appserver :
<definitions ...... > <wsp:Policy wsu:Id="PictureManagerPortBinding_MTOM_Policy-PictureManagerPortBinding_MTOM_Policy"> <ns1:OptimizedMimeSerialization xmlns:ns1="http://schemas.xmlsoap.org/ws/2004/09/policy/optimizedmimeserialization" wsp:Optional="true" /> </wsp:Policy> <!-- the wsp:Policy element is not a child of any element --> . . . <operation name="retrievePicture"> <input wsam:Action="http://service.ivan.com/PictureManager/retrievePictureRequest" message="tns:retrievePicture" /> <output wsam:Action="http://service.ivan.com/PictureManager/retrievePictureResponse" message="tns:retrievePictureResponse" /> <fault message="tns:NoShuchNumberException" name="NoShuchNumberException" wsam:Action="http://service.ivan.com/PictureManager/retrievePicture/Fault/NoShuchNumberException" /> </operation> . . <binding name="PictureManagerPortBinding" type="tns:PictureManager"> <wsp:PolicyReference URI="#PictureManagerPortBinding_MTOM_Policy-PictureManagerPortBinding_MTOM_Policy" /> . . . </definitions>


So to answer your question, yes in the case of MTOM, there are clear specifications in the WSDL ( wsp:Policy elements ) on how to encode large binary attachments into the SOAP message. For a weird reason I cannot get the SOAP attachment to work ( it's something related to my client JARs ), but you can see it in depth in Ivan Kriszan notes chapter 10.3.

And BTW , ALL binary transfers are Base64 encoded. There is no such thing as a Direct binary attachment.




PS all of this are based on what Ivan Kriszan has explained in his notes. This example is not mine.
Thanks,
Victor

Agree with you on that one , but that would imply


Either implementing sun's interface and adding an additional layer ( this was actually the first solution i implemented ), but frankly I don't know what to write in the lock() and unlock() method implementations in the interface provided by Sun. Or implementing the solution you proposed,which is nevertheless my second choice to the one I'm trying right now.



Victor

Hi Roel,

Glad you mentioned it, because i didn't think about this case.

client 1 locks record 1, then client 2 updates record 1 and finally client 3 unlocks record 1

The problem is like this : We have 3 clients.
Client 1 is locking record 1, Client 2 tries to lock record 1, but is waiting, Client 3 tries to lock record 1 but is also waiting.
Client 1 finishes it's work, Client 2 will add the lock to record 1 and so on...
This would be the normal behavior.


It might happen that after Client 2 obtains the lock, another Thread, just finishing it's job to remove the lock. Thus leaving Client 2 unable to update because a lock on that record does not exist.

The way I see it, a fix would be to increment a counter each time a record is locked, and decrement it each time a record is unlocked. What do you say?


Victor

Thaks for the reply , Roel.


Your mechanism really works ( You might know that already ) ! But I spent a hell of a lot of time on getting my class to be as Thread safe and as fast as possible ( which are two things that don't go well together), so I'm not going to choose this approach, because it involves synchronizing on the whole data object.
The more I think about it, the more I realise that I'm trying to do more than Sun asks. Basically my interface just locks one record. It does not care if multiple clients call updates or deletes on that record. Why should I care?. The data class is supposed to handle concurrent updates on the same record. This locking mechanism just saves us from a bunch of nasty mean Threads which will want to update other records while we're working.



Given what Sun asks :

Your server must be capable of handling multiple concurrent requests, and as part of this capability, must provide locking functionality as specified in the interface provided above .

I think the best solution is to go with the simple plain old lock-one-record-no-matter-what-client approach.What do you say 'bout it?

Thanks for getting my ideas straight .





Victor

Hi ,


It's locking again .

I have the following interface :

// Reads a record from the file. Returns an array where each // element is a record value. public String[] read(int recNo) throws RecordNotFoundException,DBException; // Modifies the fields of a record. The new value for field n // appears in data[n]. public void update(int recNo, String[] data) throws RecordNotFoundException,DBException; // Deletes a record, making the record number and associated disk // storage available for reuse. public void delete(int recNo) throws RecordNotFoundException,DBException; // Returns an array of record numbers that match the specified // criteria. Field n in the database file is described by // criteria[n]. A null value in criteria[n] matches any field // value. A non-null value in criteria[n] matches any field // value that begins with criteria[n]. (For example, "Fred" // matches "Fred" or "Freddy".) public int[] find(String[] criteria) throws RecordNotFoundException,DBException; // Creates a new record in the database (possibly reusing a // deleted entry). Inserts the given data, and returns the record // number of the new record. public int create(String[] data) throws DuplicateKeyException,DBException; // Locks a record so that it can only be updated or deleted by this client. // If the specified record is already locked, the current thread gives up // the CPU and consumes no CPU cycles until the record is unlocked. public void lock(int recNo) throws RecordNotFoundException; // Releases the lock on a record. public void unlock(int recNo) throws RecordNotFoundException; // Determines if a record is currently locked. Returns true if the // record is locked, false otherwise. public boolean isLocked(int recNo) throws RecordNotFoundException;


i've implemented this interface and added two additional methods :

public interface ClientAwareDBMain extends DBMain { /** * unlocks a record based on record id and client id * * @param recId * The recordId that the client wants to unlock * @param clientId * The clientId of the client that wants to unlock the record * @throws RecordNotFoundException * thrown in case recNo was not found or has been deleted. */ public void unlock(int recId, int clientId) throws RecordNotFoundException; /** * locks a record based on the clientId * * @param recId * the record id which the client wants to lock * * @param clientId * the clientId of the client that wants to lock the record * * @throws RecordNotFoundException * in case recId was not found. */ public void lock(int recId, int clientId) throws RecordNotFoundException; }


Now, when I'm writing the code, i'm reallizing that i have to alter both the public void delete(int recNo) method and the <v>public void update(int recNo,String[] data), to add an client identifier. I need a client identifier argument to identify whether a special someone does/doesn't hold the lock.
Of course, since i added another IF to my example, i could overload these two methods , to take the clientId as a parameter.


The question is :
How have you guys done this?
What have you done with the lock(int recNo) methods provided by Sun. I myself have implemented them to work using the Thread as an identifier, but annotated them with @Deprecated.



Really looking for suggestions,
Thanks,

Victor