In order to satisfy the OMG Technical Objectives, the ORB is expected to address—at least to some degree—all of the following areas:

•  Name services—The Object name-mapping services map the object names in the naming domain of the requester into equivalent names in the domain of the method to be executed. The OMG Object Model does not require object names to be unique or universal. Object location services, involving simple attribute lookups on objects, use the object names in the request to locate the method to perform the requested operation. In practice, different object systems or domains have locally preferred object naming schemes.

•  Request dispatch—This function determines the invocation method. The OMG Object Model does not require a request to be delivered to any particular object. As far as the requester is concerned, it does not matter whether the request first goes to a method that operates on the variables of objects passed as parameters, or whether it goes to any particular object in the parameter list.

•  Parameter encoding—These facilities convey the local representation of parameter values in the requester’s environment to equivalent representations in the recipient’s environment. To accomplish this, parameter encodings may employ standards or de facto standards: for example, OSF/DCE, ONC/NFS/XDR, NCA/SCS/NDR, ANSI.

•  Delivery—Requests and results are delivered to the proper location characterized by a particular node, address, space, thread, or entry point. These facilities use standard transport protocol: for example, TCP/UDP/IP, ISO/TPN.

•  Synchronization—Synchronization primarily deals with handling the parallelism of the objects making and processing a request, and the rendezvousing of the requester with the response to the request. Possible synchronization models include: asynchronous (request with no response), synchronous (request and await reply), and deferred synchronous (proceed after sending request and claim reply later).

•  Activation—Activation is the housekeeping process that is necessary before invoking a method. Activation and deactivation (passivation) of persistent objects obtains the object state for use when the object is accessed and saves the state when it no longer needs to be accessed. For objects holding persistent information in non-object storage facilities such as files and databases, explicit requests are made to objects for activation and deactivation.

•  Exception handling—Object location failures and attempted request delivery failures will report to either the requester or recipient in ways that distinguish them from other types of errors. Needed actions recover session resources and resynchronize the requester and the recipient. The ORB coordinates recovery housekeeping activities.

•  Security mechanisms—The ORB provides security enforcement mechanisms supporting higher-level security control and policies. These mechanisms ensure secure conveyance of requests among objects. Authentication mechanisms ensure identities of requesting and receiving objects, threads, address spaces, nodes, and communication routes. Protection mechanisms ensure integrity of conveyed data and ensure that the data is accessible only to authorized parties. Access enforcement mechanisms control access and licensing policies.

OMG is very active in establishing standard interfaces for object-oriented distributed systems. OMB’s CORBA is widely accepted. Vendors are developing distributed object technology tools that promise to revolutionize the software market in the 1990s. IBM, Hewlett-Packard, DEC, and many others recognize the huge market potential for object-oriented distributed systems.

Summary

This book has hopefully provided a simple and straightforward approach to the design and implementation of Oracle high-speed information systems. While many of the techniques are specific to the Oracle database, the principles apply to all areas of database management and all commercial database offerings. Hopefully, I’ve provided the knowledge and information that is required to pragmatically tune your Oracle databases.