hi manisha,
if u get a reply to this , can u please forward it to me,
i am also new to EJB..
Cheers, Hema.
----- Original Message -----
From: Manisha Menon <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, September 13, 2000 11:16 PM
Subject: Basic doubts in EJB
> Hi all,
>
> I just got subscribed to ejb mailing lists and totally
> new to ejb and to this group.
>
> So, pardon me if the doubts which I got are stupid/
> very basic level.
>
> I request you to also show me pointers, where I can
> get more information.
>
> 1. How do you map a entity container managed
> bean-field, which is not of java primitive type, but
> an instance of a composite class to database. The
> bean-field may require mapping to a table than a
> column. How can you do it ? Can I assume this is the
> limitation of CMP ?
>
> eg., for primitive data type mapping, which is fine.
>
> <object-link>
> <bean-field>beanyear</bean-field>
> <dbms-column>dbyear</dbms-column>
> </object-link>
>
> 2. Why does the multiple-result finder methods in the
> home interface of entity bean always return either a
> enumeration (JDK 1.1) and collection (JDK 1.2)
> interfaces ? Can't it return a Vector, HashMap classes
> ? Is there any restriction for the home interface ?
>
> 3. Data synchronization : Does the container-provided
> data synchronization for entity beans through
> ejbLoad() and ejbStore() is efficient ? When will
> these methods be called ? Does every vendor will have
> their own way of doing it or is there any standards
> again ? My question is, whether these methods will be
> called after every update of a field or only after
> complete update of all the fields in the bean ? I
> couldn't understand this concept. How do the container
> know the data in the bean is dirty ?
>
> <vendor> I heard that there is a flag in weblogic
> isModified(), which will determine if the data is
> dirty or not ? I am not clear about this one too
> <vendor>
>
> 4. What is the necessity of ejbPostCreate() ? Is there
> any thing to be coded here for BMP ? What is the
> significance of this method ?
>
> 5. Can't you map an entity bean with CMP to more than
> one table ? Again is that the limitation ? Whether I
> need to go for BMP in this case ? Can someone show the
> possible ways to do this with CMP ? Whether all ejb
> containers support O-R mapping tools with CMP ?
>
> 6. Dependent objects : I am sure that everyone of you
> is very familiar with dependent objects. Now when to
> instantiate this dependent objects. Assume that I am
> going for BMP. Now in which method should I
> instantiate the dependent objects ? In ejbLoad() ? In
> bean business methods ? How to do lazy initialization
> in this case ?
>
> 7. Association : How to add associations between two
> entity beans ? I am totally unclear about this.
>
> Please treat all the above questions at the very entry
> level and request you to give answers.
>
> Thank you for your patience and help,
>
> Manisha
>
>
>
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>
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