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Warum Datenbanken auch für Geo-Rasterdaten? (in German) (PDF, 192 kB) |
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rasdaman flyer (PDF, zipped, 565 kB) |
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scientific publications (external link) |
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Overview. rasdaman is middleware for management of multidimensional arrays (in the sense of programming languages) in standard databases (such as Oracle, IBM DB2, IBM Informix). Through an optimising query language rasdaman offers access to arrays of practically unlimited size The client/server architecture allows parallel multi-user access. APIs exist for C++ and Java. Additionally, the rasdaman toolkit offers a multitude of further interfaces for an optimal embedding in different environments.
Query language. Central access point to rasdaman is the array query language, rasQL. It extends ISO SQL92 <(see, e.g., SQL Reference Page for unofficial, yet comprehensive information) with multidimensional array operators, based on the rasdaman Array Algebra as mathematical foundation. This formal basis not only gives a precise definition of query results, but also forms the fundament for the server's powerful optimisation rules; currently there are about 150 such rules implemented.
Interfaces. There are APIs in C++ and Java, both conformant to the object-oriented database standard ODMG. Further interfaces allow import and export of raster data via command line or menu/browser driven. THe rasOGC component makes rasdaman a Web Map Server according to the specification of the Open GIS Consortium.
Scalability. The rasdaman server is parallelised and can handle many transactions simulteneously. A specially developed scheduler distributes incoming jobs dynamically to the server workers. These can run on the same or different machines. Rasdaman installations therefore scale smoothly from a simple PC to redundant server farms (see Fig.). This allows a perfect right sizing of rasdaman for all purposes.
Server architecture. It is perfectly legitimate to name rasdaman a database system. The multi-user parallel server is constructed along standard database architectures: client/server communcication, query parser and optimiser, execution engine, indexing, catalog, etc. The difference to other database systems is that each component has been carefully crafted towards handling large arrays, and that all components have been sync'ed in detail.
Documentation. All interfaces, as well as installation and administration, is described in detail in PDF documents, altogether about 350 pages. Additionally, the APIs are documented in HTML hypertext. A host of source code snippets show how to operate rasdaman. The manuals refer to these examples.
History. The rasdaman technology arose from research work in multimedia, graphics, and image databases done by Dr. Peter Baumann at the Fraunhofer COmputer Graphics Institute. Results were implemented in the Knowledge Bases Research Group of FORWISS. Many more research projects have contributed to the further development of this technology.