Velocis Beta-3.0 Database Server

In a nutshell, Velocis delivers all we expect of it.
  • Manufacturer: Centura Software (Raima Corporation)

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  • Price: $7,695 (eight users)

  • Reviewer: Avygdor Moise

Before I tell you about Velocis, let me tell you about my company's system and why we need a database server. Itres Research Limited is a developer of the Compact Airborne Spectrographic Imager (casi), a multispectral imaging instrument that combines the sophistication of satellite geo-positioning systems (GPS) with the practicalities of aerial photography. The casi is used worldwide in a variety of applications, and is distinguished by its high precision and flexibility of use. The casi is a user-programmable, all-digital system that is easily installed in light aircraft. It operates in the visible and near-infrared range of the spectrum. This makes it an ideal camera for forestry, agriculture, environmental monitoring, land-use planning and water-purity applications. It is widely recognized as a valuable tool in remote sensing.

One of the more important features of the casi instrument is its ability to generate absolute radiance values from the scene. In simple terms, it can not only generate color photos, but it can also tell you the absolute spectral signature of the scene. Given that most plants, minerals and other land-based objects exhibit different spectral characteristics, it is possible to classify the type of vegetation and minerals present in the photographed scene, including estimates of densities, health and concentration.

Our Problem

Precision does not come without a price. The data collected has to be passed through a number of processing steps, including radiometric correction calibration, geo-correction (the projection of each image pixel to a unique earth coordinate), mosaic (the tiling of all image strips into a single photograph) and analysis (the interpretation of the image and creation of a data product).

Before one can make use of the data, it is necessary to obtain detailed information on the casi sensor (camera) used to acquire the images (e.g., when it was last calibrated, where the latest calibration files are located, etc.) and associated flight records.

When the data processing is complete and the final report is generated, it is also highly desirable to have the means to review the parameters and tools used to process the data. This is an integral and necessary part of the quality-assurance program.

Databases Come to the Rescue (Not)

Itres' processing power is based mainly on Red Hat Linux 5.2 and 6.0. There are a number of processing stations, each equipped with dual processors (400MHz per CPU) and each connected to a 100Mbps LAN (local area network). Access to the workstation is provided by personal computers, which (unfortunately) run Windows 95. Graphic services are provided through xwin32 (an X-Windows server for Win32) in conjunction with Samba file access.

All users of Windows 95 must have access to Microsoft's Office Suite 97, primarily for editing their mail. This led to an unfortunate side effect, the availability of MS Access—the Microsoft Database engine. The need for a database solution to the information processing was so great that a number of users created private MS Access databases, which contain important processing-related information and product inventory information. There is a storage requirements database, component inventory database, customer contact database, on-line help database, flight-planning information database and the list goes on. The unfortunate part is that those databases are located on personal computers and are not easily shared among users. We attempted to move the data to our main servers which run Linux, but we met with resistance for basically two reasons:

  • The appeal, effectiveness and ease of use of the MS Access database front end.

  • The average user is not attracted to UNIX.

As a result, we searched for solutions which would enable the average user to gain access to their databases using MS Access as before, while taking advantage of the capabilities of Linux as an effective file server.

The Velocis Database Engine

We had a number of minimal requirements for a database server, and the Velocis database server 3.0 by Raima Corporation (now Centura Software) met all of them. The key features of Velocis that match our requirements are as follows:

  • Velocis application-server architecture supports multiple network communication protocols, including RPC (Remote Procedure Calls) and ODBC.

  • The Velocis application can launch and manage its own threads (starting with beta release 3.0), each thread controlling one or more Velocis “login” sessions.

  • Velocis client programs are included to give third-party ODBC database tools access to the Velocis database.

  • Velocis is available as both a client and a server for AIX, Linux, Solaris, BSDI, HPUX, Win95/98 and WinNT.

  • Velocis supports SQL 89 and a subset of SQL 92.

  • It comes with an extensive set of printed manuals (and a PDF version on CD-ROM), including User's Guide, Installation/Administration Guide, Reference Library and Language Reference (SQL and Native).

  • Velocis supports a number of database models: relational, networked and hierarchical and a combination of the three (which is how Velocis operates internally).

  • Velocis is a licensed product that is distributed on a CD-ROM or by download from Centura's web site. The cost of the license is proportional to the number of concurrent sessions supported. Without a license, it will support up to eight sessions for 60 days. During the demonstration period, Velocis is fully functional.

  • Velocis is a supported product, for a fee. The support includes product updates and consulting services in support of limited API development and product integration.