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Struts & Hibernate
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| | | How are containers handling (or supposed to handle) CMR & capture-schema iss | How are containers handling (or supposed to handle) CMR & capture-schema iss 2004-02-06 - By Stefano De Giorgi
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Hi Vineeth,
container retrieve persistence information from proprietary deployment
descriptors, where you specify
mapping column for CMP fields and mapping column for the relation field
Best Regards
Stefano
>
>
>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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