C M P   2 . 0  

is declared, the other must also be declared. The read only and read time out elements are 

described in Chapte 4 of the JBossCMP Documentation. 

R e l a t i o n s h i p   R o l e   M a p p i n g  

Each of the two ejb relationship role elements contains mapping information specific to an 

entity in the relationship.  A detailed description of the main elements follows: 

Table 9 3, ejb relationship role Tags 

Tag Name 

Description 

Required 

ejb relationship role  This is the name of the role to which this configuration  Yes 

name 

applies.  This element must match the name of one of 

the roles declared for this query in the ejb jar.xml file. 

fk constraint 

If true, JBossCMP will add a foreign key constraint to 

No, default is 

the tables.  JBossCMP will only add the constraint if 

false 

both the primary table and the related table were 

created by JBossCMP during deployment. 

key fields 

This specifies the mapping of the primary key fields of 

No, default 

the current entity.  This element is only necessary if 

depends on 

exact field mapping is desired. Otherwise, the key fields  mapping type 

element must

4

 contain a key field element for each 

primary key field of the current entity. The details of 

this element are described below. 

read ahead 

This controls the caching of this relationship. This 

No, see Chapter 

option is discussed in Chapter 6 of the JBossCMP 

6 of the 

Documentation. 

JBossCMP 

Documentation.

As noted in Table 9 3 the key fields element contains a key field for each primary key field of 

the current entity. The key field element uses the same syntax as the cmp field element of 

the entity, except that key field does not support the not null option. Key fields of a 

relation table are automatically not null, because they are the primary key of the table.  On 

4

 Note that with foreign key mapping this element can be empty; this means that there will be not be a foreign key for the current entity.  

This is required for the many side of a one to many relationship, such a Gangster in the Organization Gangster example. 

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