Object Databases: Not Just for CAD/CAM Anymore
Current limitations of the Texas library include the lack of multi-user support and the inability to query containers to find certain instances of objects. The query limitation stems from the fact that there are no containers provided with the Texas library. Most commercial object database vendors provide a set of optimized container classes that support queries. These limitations are minor if what you need is a very fast, single user, persistent store of objects. Another limitation is the inability to treat persistent and transient objects transparently. You cannot discover what heap an object is allocated on; this causes problems in objects with pointers to other contained objects. While this is a minor limitation for smaller programs, it does affect development of larger, more complex, multiple-database programs.
The future of Texas looks bright. It is a robust and efficient single user, portable library. A colleague and I are planning to port Texas to Windows NT. This will round out support for the most popular platforms, Solaris, Linux, and NT. We also plan to provide minor enhancements for the transparent treatment of the heaps. STL and a persistent allocator may provide some relief for lack of container and query support, but multi-user support is still off in the future.
Object databases are not the silver bullet of software development, but they do provide a more robust and natural programming environment for people already using an object-oriented programming language. They provide better performance and more performance tuning options than relational databases. For small to medium sized single-user projects, the Texas database is an attractive choice; for larger multi-user projects, you may want to check out ObjectStore from Object Design, Inc. ObjectStore supports a large number of platforms and compilers—unfortunately, not Linux. ObjectStore is a very fast and flexible object database product. For more information on ObjectStore, visit their home page at www.odi.com or subscribe to the ObjectStore development mailing list. (To subscribe, send e-mail to email@example.com with no subject and subscribe in the message body.)
Special thanks to Rob Murray of Quantitative Data Systems and Craig Heckman of Superconducting Core Technologies for their great comments and help.
[ORF96] Robert Orfali, Dan Harkey, & Jeri Edwards, The Essential Distributed Objects Survival Guide, John Wiley & Sons, Inc. pp. 164, 1996.
[CAT92] R.G.G. Cattell, and J. Skeen. Object Operations Benchmark, ACM Transactions on Database Systems,17(1):1-31, 1992.
[LOO95] Mary E. S. Loomis, Object Databases: The Essentials, Addison-Wesley Publishing Company, pp. 197-200, 1995.
[CAT96] R.G.G. Cattell, The Object Database Standard: ODMG - 93, Release 1.2, Morgan Kaufmann Publishers, Inc., 1996.
[SIN92] Vivek Singhal, Sheetal V. Kakkad, and Paul R. Wilson, Texas: An Efficient, Portable Persistent Store, Fifth International Workshop on Persistent Object Systems, 1992.Object Databases: Not Just for CAD/CAM Anymore.
Greg Meinke (firstname.lastname@example.org) works at Quantitative Data Systems, Inc. on distributed business systems using C++, CORBA, and ObjectStore databases.
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide