Feature

Description

Information collection

The JNDI Registry Service stores the data in a nonpersistent storage (the data is stored in the memory). Therefore, rebooting the J2EE Engine ensures that all stored objects will be removed from the naming system.

Tree-like structure

The naming contexts and objects are arranged in a hierarchy. In every context object can be placed bindings or other contexts called sub-contexts. The client gets an abstraction called “root context” as a result of the get InitialContext operation. The root context is the starting point for all following operations in the naming system.

Security

The JNDI Registry Service uses the SAP J2EE Engine Security Service to ensure maximum server security. The user authentication is performed in the get InitialContext operation and, depending on the permissions the user has, he/she will be permitted to: get InitialContext and perform all operations, perform a lookup operation only, or else he/she will not be able to get an InitialContext object at all.

Global objects

The JNDI Registry Service enables each naming operation to be replicated in the cluster – the so called global operations. Thus, in all servers’ naming systems objects appear with the same name and data. These global objects can be accessed from all over the cluster.

Client-server communication

The JNDI Registry Service uses the P4 protocol for client-server communication.

Load balancing

The JNDI Registry Service uses the SAP J2EE Engine P4 Provider Service to make the connection between the client side and one of the servers in the cluster. This server is chosen with the load balancing mechanism of the P4 Provider Service.

Non-serializable objects

All bindings in the naming system consist of an object name, serialized object data, and attributes (if provided). Only serializable objects can be kept in the naming storage. The JNDI Registry Service provides an opportunity for non-serializable objects also to be bound in the naming system, but their data is kept on the client side and they are available only to the client that has bound them.

Cache

The JNDI Registry Service provides a caching system for increasing the speed of the lookup operation. Caching is done at two levels – caching Object instances for application clients running on the server, and caching byte arrays for all other clients.

Redirection

Each remote client is using the Naming Service of one of the servers in the cluster through a context instance. This instance is connected to the naming system of this server and all naming operations are performed there. In case this server goes down, the next naming operation will be directed to another server for procession.