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Sudhir V

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Recent posts by Sudhir V

Can you resend me the invitation. seems I missed it. sudhirvallam(AT)hotmail.com
It seems in your ejobLoad method you are calling Table1 in both cases. Please check to make sure your query calls Table2.

Sudhir
You can increase the VM space consumption by specifying the -XmxMEM argument in the VM Argument list. For example if you want the VM to use 256mb of memory then u say -Xmx256m. The default memory allocation is 64mb.
15 years ago
People interested please contact me sudhirvallam(AT)hotmail.com
Multiple active Stateful, Entity EJB instances are managed by EJB Passivation. However container manages multiple inactive entity and stateless instances using pooling.
When you say "how to load bean properties in jsp" (which has to happen on the server side) "to dsplay dynamically using javascript" (client side). So it has to be a server request each time they click a + sign right unless you want to load the whole tree onto the page. I would suppose each "+" sign to be a hyperlink containing the unique id for the corresponding rootbean and upon a click reconstructs the page with data accessed using the unique id.

I don't see the use of javascript coz the page will be reconstructed by JSP. However if the tree is small you could probably load the whole tree and use layers+javascript to make visible/invisible child structure.
The implementation part is not specified in the EJB Spec and hence its upto the vendor. I would think they would generate a join sql query.
If the attributes are client specific then can be managed by the stateful beans. There are no prepackaged methods but custom accessor methods can be added in the component interface.
In most of my interviews they usually ask "how do you decide when to use Stateless vs Stateful beans". Here is the tyical answer I give

Stateful Session Bean Considerations: Stateful session beans are appropriate if any of the following conditions are true:
1)The bean's state represents the interaction between the bean and a specific client.
2)The bean needs to hold information about, or on behalf of, the client user conversational state across method invocations.
3)The bean mediates between the client and the other components of the application, presenting a simplified view to the client.
4)Behind the scenes, the bean manages the work flow of several enterprise beans.

Because stateful session beans are private to a client, their demand on server resources increases as the number of users accessing an application increases. The beans remain in the container until they are explicitly removed by the client, or are removed by the container when they timeout.
The container needs to passivate stateful session beans to secondary storage as its cache fills up and the beans in the cache timeout. If the client subsequently accesses the bean, the container is responsible for activating the bean. This passivation/activation process imposes a performance overhead on the server.

Stateless Session Bean Considerations: You might choose a stateless session bean if any of these conditions exist:
1)The bean's state has no data for a specific client, that is, user conversational state does not have to be retained across method invocations on the bean.
2)In a single method invocation, the bean performs a generic task for all clients.
3)The bean fetches a set of read-only data (from a database) that is often used by clients. Such a bean, for example, could retrieve the table rows that represent the products that are on sale this month.

Use a stateless session bean to access data or perform transactional operations. Stateless session beans provide high scalability because a small number of such beans managed by the container in a stateless bean pool) can help serve a large number of clients. This is possible because stateless beans have no association with the clients. When a request for a service provided by a stateless session bean is received, the container is free to dispatch the request to any bean instance in the pool.

Real Context example: Let say in an ecommerce site. A stateful bean can be used to maintain the state of the user. From the point he adds the first item to the cart to the point of order completion. Stateless beans can be used in the middle for non-client specific actions like getting list of all items on promotional sale.
The primary key is defined in the ejb-jar.xml and is denoted by the tag
<primkey-field>cmp field name</primkey-field> under the entity tag.

The actual mapping between the cmp field names and actual table columns is not specified as a specification in the J2EE hence each app server has its own methodology. Weblogic stores another xml file called "weblogic-cmp-rdbms-jar" where it sepcifies the mapping. Below is an excerpt

<weblogic-rdbms-jar>
<weblogic-rdbms-bean>
<ejb-name>RoomTypeEJB</ejb-name>
<data-source-name>BigRezDataSource</data-source-name>
<table-map>
<table-name>ROOMTYPE</table-name>
<field-map>
<cmp-field>description</cmp-field>
<dbms-column>DESCRIPTION</dbms-column>
</field-map>
<field-map>
<cmp-field>features</cmp-field>
<dbms-column>FEATURES</dbms-column>
</field-map>
<field-map>
<cmp-field>id</cmp-field>
<dbms-column>ID</dbms-column>
</field-map>
<field-map>
<cmp-field>maxAdults</cmp-field>
<dbms-column>MAXADULTS</dbms-column>
</field-map>
<field-map>
<cmp-field>numRooms</cmp-field>
<dbms-column>NUMROOMS</dbms-column>
</field-map>
<field-map>
<cmp-field>smokingFlag</cmp-field>
<dbms-column>SMOKINGFLAG</dbms-column>
</field-map>
</table-map>
<automatic-key-generation>
<generator-type>NAMED_SEQUENCE_TABLE</generator-type>
<generator-name>COMMON_SEQUENCE</generator-name>
<key-cache-size>1</key-cache-size>
</automatic-key-generation>
</weblogic-rdbms-bean>
<weblogic-rdbms-jar>
Please email me @ sudhirvallam(AT)hotmailcom with contact details.
Well even I don't have an idea about the project but am sure that if a group sits together then we can come up with some good ideas. I was reading about the Google API's and there's really a lot of stuff u can do with them. Like using the Google Local feature u can find businesses around you so can design an application on top of that. Mapquest also allows to use their API's so something of that sort.

Sudhir
Hi Guys

I am looking to do a fun/exiciting project using the Google API's + J2EE Technologies and was wondering if anyone would be willing to join me and probably we can form a group. We can start from scratch and develop an innovative project. I have various certifications from SUN (SCJP, SCWCD, SCBCD) and OCA 9i + J2EE handson and am expecting to form a group with people of similar skills.

Sudhir
[ December 08, 2004: Message edited by: Sudhir V ]
Hi

I am looking for any volunteer projects in J2EE based in Phoenix area or remote work.
15 years ago
Hi Guys

There's always been a debate about Hands On experience vs Certifications. I would like to share my experience on this.

I graduated with a Masters degree in May 2003 and then got an offer from a small local firm making apps in VB and data analysis. I joined the firm with a view to prepare myself for the outside market. I had already got my certification for SCJP while doing Masters. In a span of 14months I cleared SCWCD, SCBCD and OCA certifications.

My certifications did help me in getting interview calls but failed miserably in the interviews mainly involving questions on real time development and about scores of Open Source tools. I lied in my resume of having 3yrs JAVA experience and about pseudo projects or else I wud'nt have got any interview calls. Now I am looking to do some real volunteer projects using the knowledge gained from the certifications.

So really speaking its very hard to achieve the right blend of Certifications and Hand On and in my view Hands On gets an upper edge than certifications.
[ November 15, 2004: Message edited by: John Daga ]
15 years ago