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11.7 Federation of name spaces
Federating name spaces involves binding contexts from one name space into another name space. In a WAS V6 name space, federated bindings can be created with the following restrictions:
- Federation is limited to CosNaming name servers. A WebSphere name server is a CORBA CosNaming implementation.
Federated bindings to other CosNaming contexts can be created, but bindings to LDAP name server implementation contexts cannot.
| - | If JNDI is used to federate the name space, the WebSphere initial context factory must be used to obtain the reference to the federated context. If any other initial context factory implementation is used, the binding might not be created, or the level of transparency might be reduced. |
| - | A federated binding to a non-WebSphere naming context has the following functional limitations: |
JNDI operations are restricted to the use of CORBA objects. For example, EJB homes can be looked up, but non-CORBA objects such as data sources cannot.
| - | Do not federate two WebSphere single server name spaces. If this is done, incorrect behavior can result. If you require federation of WebSphere name spaces, then servers running under IBM WAS ND are required. |
In the example in Figure 11-3, assume that a name space, Namespace 1, contains a context under the name a/b. Also assume that a second name space, Namespace 2, contains a context under the name x/y. If context x/y in Namespace 2 is bound into context a/b in Namespace 1 under the name f2, the two name spaces are federated. Binding f2 is a federated binding because the context associated with that binding comes from another name space. As shown in Figure 11-3, from Namespace 1, a lookup of the name a/b/f2, would return the context bound under the name x/y in Namespace 2. Furthermore, if context x/y contained an EJB home bound under the name ejb1, the EJB home could be looked up from Namespace1 with the lookup name a/b/f2/ejb1. Notice that the name crosses name spaces. This fact is transparent to the naming client.
Figure 11-3 JNDI access using federated name spaces
