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| | | How are containers handling (or supposed to handle) CMR & capture-schema issue i | How are containers handling (or supposed to handle) CMR & capture-schema issue i 2004-02-06 - By Vineeth Varghese
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Hi folks,
I am new to CMR in EJB2.0 and was going through RMH's book Enterprise
Javabean.
I am interested in knowing how the container picks up the relationships.
I haven't exactly tried an example but am stuck without a complete
understanding of this.
In the 1-1 uni-directional relation example of customer and address, the
schema goes like this :-
Customer has a foreign key pointing to the primary key of address.
So in the example when I create a Customer bean I supply the cusomter
name, age etc and then I create the Address bean and associate the bean
with this customer bean but I want to know how is this been translated
to the underlaying database. How will the container know that the
primary key of Address should be inserted as foreign key in customer
table. I am guessing that the container will need some hint from the
developer/deployer to accomplish this. Nothing of this sort is given in
the book
I expect an anwser like "Container will extract the relationship details
from the database" :-) so if this is true but we decide to go from a
link table which maps customer_id to address_id how will the data be
inserted there.
A doubt along similar lines is regarding the one to many uni-directional
example of customers and their phone numbers. The phone number table has
a foreign key pointing to customer but the bean is developed to reverse
this relationship..i.e customer knows all his phone numbers rather than
phone knowing his customer. We do not specify anything about the foreign
keys. So when I find a customer and try to retrieve his phone numbers
how will the container know that it should query the phones table with
the customer id as the customer_id does figure in the phone bean
persistance field
I hope I am clear enough with my queries...
Note : I am deploy with the SUN J2EE implementation an using their
deploy tool
I also have a doubt which is specific to SUN J2EE 1.4 implementation.
I am trying to capture the schema details from pointbase db that come
bundled with J2ee 1.4
I am running into :-
D:\>D:\appserver\Sun\bin\capture-schema -dburl
jdbc:pointbase:server://localhost
:9092/vinman -schemaname apps -username apps -password apps -driver
com.pointb
ase.jdbc.jdbcUniversalDriver -table CustomerBean -out CustomerBean.dbschema
using dburl: jdbc:pointbase:server://localhost:9092/vinman
using username: apps
using password: apps
using driver: com.pointbase.jdbc.jdbcUniversalDriver
using schemaname: apps
java.sql.SQLException  : No suitable driver
at java.sql.DriverManager (DriverManager.java:532)
at java.sql.DriverManager (DriverManager.java:171)
at com.sun.forte4j.modules.dbmodel.jdbcimpl.ConnectionProvider.<init>(Co
nnectionProvider.java:46)
at com.sun.jdo.api.persistence.mapping.ejb.CaptureSchema.main(CaptureSch
ema.java:120)
Exception in thread "main" java.lang.NullPointerException
at com.sun.jdo.api.persistence.mapping.ejb.CaptureSchema.main(CaptureSch
ema.java:177)
I have pbembedded.jar from pointbase/lib in the classpath
Can someone please tell what I am doing wrong? Do I have to include
anything more to the classpath?
peace,
Vineeth
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<tt>Hi folks,<br>
<br>
I am new to CMR in EJB2.0 and was going through RMH's book Enterprise
Javabean.<br>
<br>
I am interested in knowing how the container picks up the
relationships. I haven't exactly tried an example but am stuck without
a complete understanding of this.<br>
<br>
In the 1-1 uni-directional relation example of customer and address,
the schema goes like this :-<br>
Customer has a foreign key pointing to the primary key of address.<br>
<br>
So in the example when I create a Customer bean I supply the cusomter
name, age etc and then I create the Address bean and associate the bean
with this customer bean but I want to know how is this been translated
to the underlaying database. How will the container know that the
primary key of Address should be inserted as foreign key in customer
table. I am guessing that the container will need some hint from the
developer/deployer to accomplish this. Nothing of this sort is given in
the book<br>
<br>
I expect an anwser like <i>"Container will extract the relationship
details from the database"</i> :-) so if this is true but we decide to
go from a link table which maps customer_id to address_id how will the
data be inserted there.<br>
<br>
A doubt along similar lines is regarding the one to many
uni-directional example of customers and their phone numbers. The phone
number table has a foreign key pointing to customer but the bean is
developed to reverse this relationship..i.e customer knows all his
phone numbers rather than phone knowing his customer. We do not specify
anything about the foreign keys. So when I find a customer and try to
retrieve his phone numbers how will the container know that it should
query the phones table with the customer id as the customer_id does
figure in the phone bean persistance field<br>
<br>
I hope I am clear enough with my queries...<br>
<b><br>
Note : I am deploy with the SUN J2EE implementation an using their
deploy tool<br>
<br>
</b>I also have a doubt which is specific to SUN J2EE 1.4
implementation.<br>
<br>
I am trying to capture the schema details from pointbase db that come
bundled with J2ee 1.4<br>
I am running into :-<br>
<br>
D:\>D:\appserver\Sun\bin\capture-schema -dburl
jdbc:pointbase:server://localhost<br>
:9092/vinman -schemaname apps -username apps -password apps -driver
com.pointb<br>
ase.jdbc.jdbcUniversalDriver -table CustomerBean -out
CustomerBean.dbschema<br>
<br>
using dburl: jdbc:pointbase:server://localhost:9092/vinman<br>
using username: apps<br>
using password: apps<br>
using driver: com.pointbase.jdbc.jdbcUniversalDriver<br>
using schemaname: apps<br>
java.sql.SQLException : No suitable driver<br>
at java.sql.DriverManager (DriverManager.java:532)<br>
at java.sql.DriverManager (DriverManager.java:171)<br>
at
com.sun.forte4j.modules.dbmodel.jdbcimpl.ConnectionProvider.<init>(Co<br>
nnectionProvider.java:46)<br>
at com.sun.jdo.api.persistence.mapping.ejb.CaptureSchema.main(CaptureSch<br>
ema.java:120)<br>
Exception in thread "main" java.lang.NullPointerException <br>
at com.sun.jdo.api.persistence.mapping.ejb.CaptureSchema.main(CaptureSch<br>
ema.java:177)<br>
<br>
<br>
I have pbembedded.jar from pointbase/lib in the classpath<br>
<br>
Can someone please tell what I am doing wrong? Do I have to include
anything more to the classpath?<br>
</tt><tt> <br>
<br>
peace,<br>
Vineeth</tt><font size="-1"><br>
<br>
</font>
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