Armed with planet-size marketing budgets and leveraging their position as leaders in the RDBMS market, IBM Corp., Informix Software Inc., and Oracle Corp. have cornered most of the mindshare for their "Universal Servers." But a handful of smaller DBMS vendors offer database servers that integrate relational and object DBMS features. These vendors include UniSQL Inc., Unisys Corp., and Unidata Inc.
The following scenario illustrates how these object-oriented and relational features can work together. A front-end application can submit a query as a SQL SELECT statement. UniSQL/X can place the result set along with Object IDs in memory. The client application can then issue API calls to navigate these Object IDs in order to access data that may naturally have a complex nested or hierarchical structure.
UniSQL's strategy covers both the database server and middleware approaches. UniSQL has marketed an enhanced version of UniSQL/X named UniSQL/M. The "M" stands for "multidatabase" integration because this version of the database server can connect to other relational, object-oriented, hierarchical, flat file, and other legacy data sources; it presents a unified global view of heterogeneous data. The next version of UniSQL/M will be renamed InfoBroker, and it should be shipping in July 1997. InfoBroker uses native drivers to access data sources. InfoBroker's metadata schema can represent integrated data as tables or as object-oriented classes with inheritance, methods, and so forth. The data is accessible by clients using ODBC and by object-oriented C++ applications.
UniSQL's future plans include improved support for Java, a cartridge facility comparable to DataBlades, and an SMP port for parallel processing in the server. The first cartridges will support image pattern matching (using software from Excalibur Technologies) and text processing (using Verity Inc.'s technology). UniSQL already has extensions for managing multimedia and for integrating with Web servers and browsers.
ODBC and embedded SQL can be used to query a database, or C++ and Smalltalk applications can navigate objects based on relationship references (described in the next paragraph). Osmos also supports ad hoc queries through its Object Manipulation Language, which is based on a combination of the SQL3 draft and the Object Database Management Group (ODMG; www.odmg.org) Object Query Language (OQL). Osmos extends the SQL3 concept of reference-based relationships (as opposed to value-based relationships as used in RDBMSs) by allowing relationships between classes and objects to be defined in bidirectional terms. Referential integrity constraints can be defined for these inverse relationships. Relationship types can be single-valued, collections such as multisets (unordered with duplicates allowed), sets (unordered but no duplicates), or a list (ordered with duplicates allowed).
Unisys first deployed Osmos internally in the early 1990s. In 1994, the first commercial installation occurred at Bellcore, a telecommunications company. In late 1995, Unisys announced the general commercial availability of Osmos. Osmos currently runs on Sun Solaris, HP-UX, Unix SVR4, UnixWare, and Windows NT.
Return to "Universal Servers: The Players" by Judith R. Davis
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