Biomedical Engineering Reference
In-Depth Information
Interfaces
Databases don't stand alone, but communicate with devices and users through external and user
interfaces, respectively. Getting data into a database can come about programmatically as in the
creation of a data warehouse or data mart through processing an existing database. More often, the
data are derived from external sources, such as user input through keyboard activity, or devices
connected to a computer or network.
Common sources of input data include mouse and keyboard activity, voice recognition, bar-code
readers, wireless devices, and RF-ID tags. Electronic data recorders, sequencing machines, and a
variety of test equipment can also provide data for inclusion in the database, according to device
communications standards. A variety of standards, such as the IEEE 1073 Point of Care Medical
Device Communications standard, define the format, speed, and protocol of communications between
workstations and external devices (see
Figure 2-19
).
Figure 2-19. External Interfaces. Databases communicate with equipment
and users through a variety of external interfaces.
Getting data into a database is of little value unless the data can also be retrieved. As illustrated in
Figure 2-19
, the most common methods for extracting data from a database are based on the
Internet or an intranet and languages such as the Common Gateway Interface (CGI), the PHP:
Hypertext Processor (PHP), and Java. In each case, the user issues a command from the workstation
that is interpreted in the server. Results of the database query are then processed by language
system and HTML is sent to the user's browser. In this scenario, the computational overhead is borne
by the server.
Each system handles high-level database queries differently. For example, to perform a query using
CGI, the user submits a query through a Web browser and the server executes a program, a CGI
script, and the user's query is passed to the database via CGI. The program then returns information
to the server via CGI, and this information is formatted into an HTML Web page that is displayed
through the user's browser.
Similarly, the PHP interface offloads database query functions to the server, which handles the query,
formats results, and conveys these to the user via standard HTML. Although PHP, which was
