An OPC server has subsystems addressing functions such as data access,
alarms and events, and historical data. The OPC server can interact with other
applications such as Microsoft Excel, a web browser, or any ODBC database.
One analogy to an OPC configuration may be the use of printer drivers on
PCs. Rather than have each application on a PC have a driver for a printer,
one driver is used for all applications. This eliminates duplication, inconsisten-
cies and conflicts.
Interoperable Smart Building System Databases
Each technology system in a smart building has some sort of data or database
associated with its operation. Such data may also be required by another tech-
nology system, may be partially duplicated in another technology or manage-
ment system, or may be needed by a business administration system. Major
database standards allow for the access to or transfer of database information
within smart building systems.
Structured Query Language
The Structured Query Language is a standard (ISO and ANSI) that defines
rules for the definition, structure, operation, manipulation, and management
of relational databases. The first SQL standard was adopted in 1986 and there
have been several additions, expansions and modifications of the standard
since then. SQL is a vital and integral part of open network architecture
necessary for smart buildings because it allows for databases from different
manufacturers to interoperate and exchange data (Fig. 2.9).
IBM is recognized for developing the initial SQL format and rules that were
later used to draft the SQL standard. Other major manufacturers have adopted
the standard and market products compliant with SQL, including Microsoft,
Sun, Oracle, and others. Many of these manufacturers have proprietary add-
ons or extensions of the SQL standard. SQL can run on a variety of hardware
(PCs, servers, mainframes), a variety of networks (local, wide, enterprise), and
a variety of operating systems (MS Windows, UNIX, Linux, Mac).
SQL uses a row-and-column structure much like the spreadsheet applications
used by many PC users. The initial purpose of SQL was to make it easy to query
databases, but SQL has evolved to a full complement of programming, security,
and management tools. Users can query data and programmers can program
with simple sentences. Because the programming and user interfaces are simple
and intuitive, data are more accessible and usable.
The Foundations of a Smart Building 25