HS configuration data is stored in the data dictionary of the Oracle database server. Because the agent may be remote and may therefore be administered separately, several circumstances can lead to configuration mismatches between servers and agents. For example:
An agent can be newly installed on a separate computer so that the server has no Heterogeneous Services data dictionary content to represent the agent's Heterogeneous Services configuration data.
A server can be newly installed and lack the necessary Heterogeneous Services configuration data for existing agents and non-Oracle data stores.
A non-Oracle instance can be upgraded from an older version to a newer version, requiring modification of the Heterogeneous Services configuration data.
A Heterogeneous Services agent at a remote site can be upgraded to a new version or patched, requiring modification of the Heterogeneous Services configuration data.
A database administrator (DBA) at the non-Oracle site can change the agent setup, possibly for tuning or testing purposes, in a manner which affects Heterogeneous Services configuration data.
Agent self-registration permits successful operation of Heterogeneous Services in all these scenarios. Specifically, agent self-registration enhances interoperability between any Oracle database server and any Heterogeneous Services agent (if each is Version 8.0.3 or higher). The basic mechanism for this functionality is the ability to upload Heterogeneous Services configuration data from agents to servers.
Self-registration provides automatic updating of Heterogeneous Services configuration data residing in the Oracle database server data dictionary. This update ensures that the agent self-registration uploads need to be done only once, on the initial use of a previously unregistered agent. Instance information is uploaded on each connection, not stored in the server data dictionary.