JNDI interoperability considerations
This section explains considerations to take into account when interoperating with WAS V4.0 and with non-WebSphere Application Server JNDI clients. Also, the way resources from MQSeries must be bound to the name space changed after V4.0 and is described below.
Interoperability with WAS V4.0
- EJB clients running on WAS V4.0 accessing EJB applications running on WAS V5 or V6
Applications migrated from previous versions of WAS may still have clients still running in a previous release. The default initial JNDI context for EJB clients running on previous versions of WebSphere Application Server is the cell persistent root (legacy root). The home for an enterprise bean deployed in v5 or 6 is bound to its server's server root context. In order for the EJB lookup name for down-level clients to remain unchanged, configure a binding for the EJB home under the cell persistent root.
- EJB clients running on WAS V5 or V6 accessing EJB applications running on WAS V4.0 servers
The default initial context for a WAS V4.0 server is the correct initial context. Simply look up the JNDI name under which the EJB home is bound.
Note: To enable WebSphere Application Server V5 or V6 clients to access v4.x servers, the down-level installations must have e-fix PQ60074 installed.
EJB clients running in an environment other than WebSphere
Application Server accessing EJB applications running on WebSphere Application Server V5 or V6 serversWhen an EJB application running in WAS V5 or V6 is accessed by a non-WebSphere Application Server EJB client, the JNDI initial context factory is presumed to be a non-WebSphere Application Server implementation. In this case, the default initial context will be the cell root. If the JNDI service provider being used supports CORBA object URLs, the corbaname format can be used to look up the EJB home. The construction of the stringified name depends on whether the object is installed on a single server or cluster, as shown below.
- Single server
initialContext.lookup( "corbaname:iiop:myHost:2809#cell/nodes/node1/servers/server1/myEJB");
According to the URL above, the bootstrap host and port are myHost and 2809, and the enterprise bean is installed in a server server1 in node node1 and bound in that server under the name myEJB.
initialContext.lookup(
"corbaname:iiop:myHost:2809#cell/clusters/myCluster/myEJB");
According to the URL above, the bootstrap host and port are myHost and 2809, and the enterprise bean is installed in a server cluster named myCluster and bound in that cluster under the name myEJB.
The above lookup will work with any name server bootstrap host and port configured in the same cell.
The above lookup will also work if the bootstrap host and port belongs to a member of the cluster itself. To avoid a single point of failure, the bootstrap server host and port for each cluster member could be listed in the URL as follows:
initialContext.lookup(
"corbaname:iiop:host1:9810,:host2:9810#cell/clusters/myCluster/myEJB");
The name prefix cell/clusters/myCluster/ is not necessary if boostrapping to the cluster itself, but it will work. The prefix is needed, however, when looking up enterprise beans in other clusters. Name bindings under the clusters context are implemented on the name server to resolve to the server root of a running cluster member during a lookup; thus avoiding a single point of failure.
If the JNDI initial context factory being used does not support CORBA object URLs, the initial context can be obtained from the server, and the lookup can be performed on the initial context as follows:
Hashtable env = new Hashtable(); env.put(CONTEXT.PROVIDER_URL, "iiop://myHost:2809"); Context ic = new InitialContext(env); Object o = ic.lookup("cell/clusters/myCluster/myEJB");
In releases previous to WAS V5, the MQSeries jmsadmin tool could be used to bind resources to the name space. When used with a WebSphere Application Server V5 or V6 name space, the resource is bound within a transient partition in the name space and does not persist past the life of the server process. Instead of binding the MQSeries resources with the jmsadmin tool, bind them from the WAS administrative console, under Resources in the console navigation tree.