For example, using Figure 1, the value of a logical name, for example, the translation of DISK$SCRATCH varies depending upon which process context the name is translated:
|Process ID||Translation of DISK$SCRATCH|
Alternatively, the translation of the logical name MASTERFILES also varies by which process context the translation is performed in:
|Process ID||Translation of MASTERFILES|
|Figure 1. Different Logical Name environments for different users and groups (from Inheritance based Environments for OpenVMS Systems and OpenVMS Clusters, Gezelter, February 2004)|
The integration of the Logical Name facility with the Record Management Services (referred to as "RMS") Open facility yields a far more powerful mechanism than the environmental parameters used on *IX and Windows. The filename supplied to RMS may include an integral logical name, which will be automatically translated. For example, a file PHONELIST.DAT located in the directory pointed to by the MASTERFILES logical name would be specified as MASTERFILES:PHONELIST.DAT.
RMS is another area where OpenVMS has taken a fundamentally different architectural path than *NIX and Windows. RMS is a universal toolkit that defines a variety of file types (sequential, relative, indexed) and provides defined, automatic ways for programs to access the contents of a file without the need for awareness of the underlying file format. Thus, the TYPE utility produces reasonable results regardless of the underlying file type. Using TYPE on an index file yields the actual data records in order by their primary key without anything more than a simple OPEN. In modern terminology, OpenVMS RMS provides an object-oriented toolkit for managing files. However, RMS, which was part of the original VAX/VMS design, predates the popularity of the object-oriented paradigm by at least a decade.
Similarly, the shareable library facility, which on a system-wide level is a technology fundamental to the use of the Common Runtime Library, is fully available to normal users and provides the ability to implement extremely flexible environments in a simple, yet powerful manner. A more complete presentation of the use of shareable libraries may be found in presentations from the 1996 Spring DECUS symposium: OpenVMS Shareable Libraries: An Implementor's Guide and Case Studies in OpenVMS Shareable Libraries.
OpenVMS is also notable in that it uses neither an open-source, nor a closed-source model. Instead, the OpenVMS model is better described as visible-source. Since the first release of OpenVMS in 1978, the overwhelming majority of the source listings have been available for purchase at nominal cost, originally on microfiche, presently on CDROM. The interfaces needed to write device drivers and other privileged extensions of the operating system have been well documented for the entire life of OpenVMS.
Since 1997, OpenVMS has been available for free for personal, non-commercial use. This program, known as the Hobbyist program has issued over 644,000 licenses. Details about the Hobbyist program are available at http://www.OpenVMSHobbyist.org. Unrestricted commercial licenses are available with the actual price depending upon the architecture and size of the system. Licenses are also available to developers under Hewlett Packard's Developer and Solution Partner Program (DSPP).
Now approaching its 30th anniversary, OpenVMS continues to seamlessly add new capabilities, while continuing the hallmark features that have made it the first choice for many mission-critical applications, across the full spectrum of computing from desktop to datacenter.
About the author:
Robert Gezelter, CDP, Software Consultant, guest lecturer and technical facilitator has more than 25 years of international consulting experience in private and public sectors. Mr. Gezelter is a regular guest speaker at technical conferences world-wide such as HPETS (formerly DECUS).
He has worked extensively in OpenVMS since its initial release as VAX/VMS in 1978. He consults extensively on computer architectures, operating systems, APIs, networks, security, and related matters.
Among his published work are articles appearing in Network World, Open Systems Today, Digital Systems Journal, Digital News, The OpenVMS Technical Journal, and Hardcopy. Mr. Gezelter also writes a Column and serves as a Contributing Editor on OpenVMS.org, a www site serving the OpenVMS community. He is also a contributor to the Computer Security Handbook, 4th Edition (Wiley, 2002) and the "OpenVMS Security" and "Internet E-Mail Architecture" chapters of the Handbook of Information Security (Wiley, 2005).
Mr. Gezelter can be reached via his firm's www site at http://www.rlgsc.com.
- "OpenVMS, 1/2"
- "OpenVMS, 2/2"